how can i transfer music from iphone 4 to iphone 5

Sync it from your iTunes library to your iPhone 5. You can also re-download iTunes purchased content directly on your phone. Quicker to just sync it though. Your music is in your iTunes library, correct? And you regularly backup this data, correct?

iTunes is the central database for music. Whatever you have on the older iPhone should also be in iTunes, assuming you have been keeping them in sync. If so, then syncing the new iphone to itunes will let you sync the music to it.

If you use itunes match, that's a different situation, but you haven't indicated that you use it.

Check this info.

http://support.apple.com/kb/HT2109