OK, you have not just commented out the themes, but removed several bits that the code needs (I think). I see you only want flags, no theme choice, and you want them centered. This is the same as I have.
Try the following code, and see if it is what you want.
<?php
// ------------------------------------------------------------------------- //
// Coppermine Photo Gallery 1.2.0 //
// ------------------------------------------------------------------------- //
// Copyright (C) 2002,2003 Gregory DEMAR <gdemar@wanadoo.fr> //
// http://www.chezgreg.net/coppermine/ //
// ------------------------------------------------------------------------- //
// Updated by the Coppermine Dev Team //
// see /docs/credits.html for details //
// ------------------------------------------------------------------------- //
// This program is free software; you can redistribute it and/or modify //
// it under the terms of the GNU General Public License as published by //
// the Free Software Foundation; either version 2 of the License, or //
// (at your option) any later version. //
// ------------------------------------------------------------------------- //
starttable("100%"); ?>
<tr>
<td class="tableb" align="center">
<?php print cpg_show_flags(); ?>
</td>
</tr>
<?php endtable(); ?>
<?php
function cpg_show_flags()
{
// ------------------------------------------------------------------------- //
// ChooseLanguageByFlag.mod v1.3 for Coppermine Photo Gallery 1.1.0 (final) //
// by GauGau (Joachim Mueller) http://gaugau.de/ //
// ------------------------------------------------------------------------- //
// ---edit below vars--- //
$choice= "flag";
//edit this: choose between "flag" (pictures of flags), "list" (dropdown box) "both" or "none"
$theme_choice= "none";
//edit this: choose between "pulldown" (dropdown box), "links" (horisontal list of links) or "none"
$number_of_rows=1;
// edit this value: how many rows of flags should be shown (it makes sense to//
// have more than 1 row if you have you coppermine navigation not on top of //
// the page (horizontally) but on the side of the gallery (vertically). //
// Usually (with most themes) this value can be set to 1 //
$border_flag_color = "#000000";
//do you want a border around your flag? Set the color here, leave blank if //
// you don't want a border. Use color codes that css understands, e.g. //
// "#FF0000" or "red". //
// For more details on color codes, check //
// http://www.w3.org/TR/REC-CSS1#color-units/ //
$translate_language = "Language: ";
$select_theme = "Theme: ";
// edit this: translate "Sprache" to the word "language" in your country or //
// whatever text you want to appear in front of the flags/dropdown box //
// Use below arrays to specify which countries should show up. The expression//
// in brackets must be the name of the language file (without the ".php" at //
// the end). The first array specifies the "realname" of the language, the //
// second arry must contain the country code (see the folder /images/flags) //
// and must correspond to the image. Example: if you want the stars and //
// stripes turn up instead of the union jack, use //
// $language_name['english'] = 'English'; $country_code_flag['english'] = 'gb';
$language_name['spanish'] = 'Castellano (Spanish)'; $country_code_flag['spanish']= 'es';
$language_name['english'] = 'English'; $country_code_flag['english'] = 'gb';
$language_name['french'] = 'Francais (French)'; $country_code_flag['french'] = 'fr';
$language_name['italian'] = 'Italiano'; $country_code_flag['italian'] = 'it';
// ------------------------------------------------------------------------- //
//---------don't edit below this line unless you know hat you're doing-------- //
// ------------------------------------------------------------------------- //
global $CONFIG,$USER;
// get the current language
$cpg_current_language=$CONFIG['lang'];
if($USER['lang']!=""){$cpg_current_language=$USER['lang'];}
if($_GET['lang']!=""){$cpg_current_language=$_GET['lang'];}
$cpg_current_theme=$CONFIG['theme'];
if($USER['theme']!=""){$cpg_current_theme=$USER['theme'];}
if($_GET['theme']!=""){$cpg_current_theme=$_GET['theme'];}
//get the url and all vars except $lang
$cpg_current=$_SERVER["SCRIPT_NAME"]."?";
foreach ($_GET as $key => $value) {
if ($key!="lang"){$cpg_current.= $key . "=" . $value . "&";}
}
$cpg_current.="lang=";
//get the url and all vars except $theme
$cpg_theme=$_SERVER["SCRIPT_NAME"]."?";
foreach ($_GET as $key => $value) {
if ($key!="theme"){$cpg_theme.= $key . "=" . $value . "&";}
}
$cpg_theme.="theme=";
//set the border
if ($border_flag_color!="")
{
$flagborder='style="border-width:1px; border-color:'.$border_flag_color.'; margin:0px;"';
}
if($choice=="flag" || $choice=="both")
{ //----------------flags start
$cpg_flags_total=count($language_name);
$cpg_flags_cols=ceil($cpg_flags_total/$number_of_rows);
$cpg_flag_return='<style type="text/css"><!-- .winzig {font-size:9px} --></style>';
if ($number_of_rows!=1) $cpg_flag_return.= '<hr />';
$cpg_flag_return.= '<span class="winzig">' . $translate_language .'</span>';
if ($number_of_rows!=1) {$cpg_flag_return.='<br />';}else{$cpg_flag_return.='';}
$cpg_flag_return.= '';
$cpg_flags_counter=1;
foreach ($language_name as $key => $value)
{
$cpg_flag_return.= ' <a href="' . $cpg_current . $key . '" class="menu"><img src="images/flags/' . $country_code_flag[$key] . '.gif" width="24" height="13" border="1" alt="" title="' . $value .'" '.$flagborder.' /></a> 
';
if($cpg_flags_counter==$cpg_flags_cols){$cpg_flag_return.="</td><!--<td class='tableb'>";$cpg_flags_counter=0;}
$cpg_flags_counter++;
}
} //----------------flags end
if($choice=="list" or $choice=="both")
{ //----------------list start
if ($number_of_rows==1 and $choice=="both"){$cpg_flag_return .='';}
$cpg_flag_return.="<form name=\"choose_language\" action=\"" . $cpg_current . $key. "\" method=\"get\" style=\"margin-top:0px;margin-bottom:0px\"><span class=\"winzig\">";
if ($choice=="list")
{
if ($number_of_rows!=1) {$cpg_flag_return .= '<hr />' . $translate_language;}else{$cpg_flag_return.='';}
}
$cpg_flag_return.=$translate_language . "<select name=\"lang\" size=\"1\" onchange=\"if (this.options[this.selectedIndex].value) window.location.href='".$cpg_current."' + this.options[this.selectedIndex].value;\">";
foreach ($language_name as $key => $value)
{
$cpg_flag_return.='<option value="' . $key . '"';
if($key==$cpg_current_language){$cpg_flag_return.=' selected';}
$cpg_flag_return.='>' . $value . '</option>';
}
$cpg_flag_return.= '</select></span></td><td class="tableb">';
} //----------------list end
if ($theme_choice== "links")
{ // start links menu
$cpg_flag_return.='<span class="winzig">' .$select_theme;
$cpg_flag_return.='<a href="'.$cpg_theme.'default">Default</a> | ';
$cpg_flag_return.='<a href="'.$cpg_theme.'blue_tatoo">Blue Tatoo</a> | ';
$cpg_flag_return.='<a href="'.$cpg_theme.'eyeball">Eyeball</a> | ';
$cpg_flag_return.='<a href="'.$cpg_theme.'fruity">Fruity</a> | ';
$cpg_flag_return.='<a href="'.$cpg_theme.'hardwired">Hardwired</a> | ';
$cpg_flag_return.='<a href="'.$cpg_theme.'hsocuk">HSOCUK</a> | ';
$cpg_flag_return.='<a href="'.$cpg_theme.'igames">Igames</a> | ';
$cpg_flag_return.='<a href="'.$cpg_theme.'mac_ox_x">Mac OS X</a> | ';
$cpg_flag_return.='<a href="'.$cpg_theme.'project_vii">Project VII</a> | ';
$cpg_flag_return.='<a href="'.$cpg_theme.'rainy_day">Rainy Day</a> | ';
$cpg_flag_return.='<a href="'.$cpg_theme.'water_drop">Water Drop</a> | ';
$cpg_flag_return.='<a href="'.$cpg_theme.'xxx">Reset theme</a>';
$cpg_flag_return.='</span>';
$cpg_flag_return.="</form>";
} // end links menu
else if ($theme_choice== "pulldown"){ // start pul-down menu
$cpg_flag_return.="<form name=\"choose_theme\" action=\"" . $cpg_theme."&theme=\" method=\"get\" style=\"margin-top:0px;margin-bottom:0px\"><span class=\"winzig\">";
$theme_name['default'] = 'Default';
$cpg_flag_return.=$select_theme . "<select name=\"theme\" size=\"1\" onchange=\"if (this.options[this.selectedIndex].value) window.location.href='".$cpg_theme."' + this.options[this.selectedIndex].value;\">";
foreach ($theme_name as $key => $value)
{
$cpg_flag_return.='<option value="' . $key . '"';
if($key==$cpg_current_theme){$cpg_flag_return.=' selected';}
$cpg_flag_return.='>' . $value . '</option>';
}
$cpg_flag_return.= '</select></span>';
} // end pul-down menu
if ($number_of_rows==1){$cpg_flag_return.='<!--foo</td></tr></table>-->';}
$cpg_flag_return.='';
return $cpg_flag_return;
} //--- def function cpg_show_flags end
function cpg_ascii_onoff()
{
$cpg_current=$_SERVER["SCRIPT_NAME"]."?";
foreach ($_GET as $key => $value) {
if ($key=="ascii"){
$ascii_exist=1;
if ($value==1){$value=0;}else{$value=1;}
}
$cpg_current.= $key . "=" . $value . "&";
}
if($ascii_exist!=1){$cpg_current.="ascii=1";}
$cpg_current = rtrim($cpg_current , "&");
return $cpg_current;
}
?>
This is based on your code for languages.