Itunes certificate help please

So one day I was messing around and i installed this certificate/keychain, and it messed things up a bit, so i went and deleted it. Well it turns out that i deleted it and some other certificate/keychain that held all my login information for iTunes. Now, i can't download anything from the mac app store or the iTunes store. It won't even let me search for things. Ive searched EVERYWHERE for a solution to this, it appears that I'm the only person who is dumb enough to do this. Please help me out here, I'm waaaay out of my depth here.

Apple's Keychain Access application includes a Keychain First Aid function.
After you bring up the First Aid dialog box in Keychain Access, you can launch a verification procedure that checks for corrupt entries and tries to repair them.

If you're left with entries you can't reclaim, or your Mac continues to misbehave after you instigate repairs, you may be forced to delete your Keychain preference file, remove troublesome Keychain entries, substitute files from a current system backup or reset your Keychain to its defaults in Keychain First Aid.
Although a reset cures problems with the Keychain itself, it also empties it out, leaving you to recreate your saved items one by one.

SM