I accidentally deleted itunes, how do I get it back with all my songs on it?

Do you not have and maintain a Backup of your Precious music and data...

I take it you mean you've unistalled iTunes?

If so, the music will still be on the computer, just reinstall iTunes from here: http://www.apple.com/itunes/download/

(If you've deleted the iTunes folder then it'll be in trash, but only if you have a small library. Otherwise if you don't have a back up then it's bad news although you can still recover the music music purchased from iTunes by clicking on "Purchaed" in the iTunes store.)