Can someone help me with iTunes?

The songs on your phone came from your computer, on itunes? If so, the music on your phone is basically only there because you sync it from itunes. It relies on the song files actually being on your computer to be able to sync. If the actual songs are not at all on your computer, this means your songs are gone and were lost when you had your computer cleaned. Try making sure you are logged into your itunes account, and make sure to check the purchased tab to see if the songs show up there (if you bought the songs from itunes). Do you have your songs backed up on a hard drive or disk? If so, you can re-add them from there. If you have your songs from cd's, you will have to re-save them. If not, sadly there's nothing else you can do but re-buy the music. In the future, always make sure you have your music (or anything else important) backed up on a external hard drive so you don't lose anything. I only know because that's happened to me.

I feel you. Download this: http://www.getsharepod.com/

The trial version is enough to get the job done, so it's completely free. I've used Sharepod time and time again. Works like a charm!

Just in case this happens again for whatever reason, you should back up all your files onto an external hard drive. It'll make your life a whole lot easier if you ever have to restore your computer.

To my knowledge you can't