There might be several of them, that could have that impact - maybe you have edited include/themes.inc.php. Impossible to tell for sure - I can just look at the output and make a guess. You should really take a note when you edit core code. To undo any possible edits, perform an
update as suggested in the docs. In fact you are running an outdated version (cpg1.4.24, as the most recent stable release currently is cpg1.4.25), so you should upgrade anyway. On the way, this should undo all your edits. Before you perform the upgrade though, you need to do as suggested in the docs as well and
rename your custom theme first: you haven't, so your theme still runs under the name "classic", which is just plain silly and dangerous in terms of upgrading.