Search function not working

[Ajeh]

Could you check in phpMyAdmin that all of your Products have master_categories_id values ...

Also have you applied all of the Known Bug Fixes:
http://www.zen-cart.com/forum/showthread.php?t=82619

NOTE: this is also a good time to check that you have applied all of the Security Patches and Updates:
http://www.zen-cart.com/forum/showthread.php?t=131115

[AlfaOttoParts]

Yes they all have numbers. Some are the same number, which I am assuming is just to signify being in the same category. Tried to look around to see any issues, not much that I can tell though.

As far as I know, all the patches have been updated.

[Ajeh]

Your best bet might be to get a clean Zen Cart and compare the code to your site with something like Beyond Compare from scootersoftware.com ...