How to transfer all your mp3 files from media player to iPhone?

I have automatically synced the phone to my music files but not all the files are transferred. What are the steps to manually transfer them?

Just add the mp3 files to your music list in itunes, then you can copy them to the iphone, I do this all the time.

You can try 4Videosoft iPad Manager Platinum to transfer all your MP3 files to iPhone. It's very easy to use. Search more information on the website and have a free try.