The joy of iTunes
When you try to launch iTunes.Do you get the iTunes menu bar on the top of your screen?
If thats the case,the iTunes window is mostly under your dock...
If you open iTunes and the application just quits.
It could be multiple things.
I will list the 3 main ones.
iTunes plugs ins
If you hold down Option+Cmd when you click on iTunes,its boot iTunes in safe mode.If that works.you know the problem then.
ITunes library
If you hold down option when you open iTunes,if you get a prompt to chose your iTunes library and you select create library and iTunes works.
Your iTunes library is corrupted.
Personal Settings for iTunes
If you go into Home->Library->Preferences and delete com.iTunes.plist
And you can launch iTunes after that,you issue was your personal settings.
If that all Fails.
Create a another account on the computer.
If iTunes has the same problem,your issue is system wide.
But the fact you did a A&I its most likely something is messed up inside your user account