how do i transfer ipod music to new computer. Lost all data on old computer

You cannot transfer song files from iPod to computer using iTunes (except for songs purchased from the iTunes Store). However, there are third-party methods and utilities that can transfer song files from iPod to computer. If you do a Google search on something like "ipod transfer," you should get some links.

NOTE: Songs previously purchased from the iTunes Store can also be re-downloaded at no cost, from the iTunes Store Purchased screen.