How do I re-populate iTunes from my iPhone?

My Mac hard drive crashed. The disk was lost completely. The Apple store staff gave me a new hard drive, which is a basic OS load. I need to get the contents of my iPhone (music, contacts, the few photos I have left) transferred to the iTunes library. How do I get the iTunes library to load from the phone?

The iTunes library is connected to an old Apple ID no longer in use. I need to give it my Apple ID and then have it download my songs. This must be a common problem with people who have lost their computer or hard disk. How do I do it?

Desperately trying to save music library loaded by hand from old vinyl and CDs...