Thanks for your suggestions but neither seem to apply to my problem! I have downloaded to my computer first - they play fine on computer, but when I copy to MP3 Player, no data is transferred - just the title!
It could be that wherever you copied the music from it is either not MP3 so not compatible with your MP3 player or its some form of copy protection and you are only allowed to use it on the device it was downloaded to. To stop you copying it again. Suggest you contact whatever website it was you got the music off, or look in their FAQs.
It could be DRM but some MP3s have issues with compression problems. They'll play on some PC media players (such as Winamp) then won't play on others such as Windows Media Player (goes orange in the playlist with a ! sign and skips to the next track). This is the same with MP3 players - mine's an iRiver and usually plays anything I give it, but some are just strange and won't play and usually skip to the next track. It probably needs to be opened with an audio editing program and converted again to MP3 to correct it. Or you could burn them to CD then rip them back as MP3.
Success! Thanks everyone for your help - all I had to do was burn to CD and rip back to WMP - (kept them as WMA files) then transfer to MP3 Player (perhaps I could have done it direct from CD to MP3 Player?). Anyway - all is o.k. now and I have learned a lot today!