I have an Inspiron 1520 that I got from my parents. I went an started uninstalling a whole bunch of crap that they added. I think I may or may not have messed up my sound cards. In browser, no sound. In Steam (Gaming platform), no sound. In one game, WWII Online, I have sound. No where else does sound work. Under Steams "System Specs" page it lists that I have no sound card installed. Before, I had Sigmatel installed, and it says I still do. I went to the dell website, got the sound card for my computer, and when I tried to install it it said something about it not being for the correct computer. Help!

have you tried the Add New Hardware applet in control panel? Also what does the Device Manager say about the sound card? Another place to check is the Sound applet and see where the default audio device is pointing to.

you could try right clicking on 'my computer' choose properties, hardware, device manager, sound video and game controllers, right click the audio device, click properties, drivers, update drivers. may help, alternatively if you have recently updated these drivers you could try rolling back to the previous driver and see if that works, my humble opinion only.

Try using System Restore to restore back to the restore point at which sound worked.
Don't uninstall applications unless you understand just what resources you are removing.