YAY!!!
Oh.....I should really say how
It took me ages, but it really is a simple process - I went into "Testing Mode" as ScrapMaker suggested
I downloaded Storage Manager and formated my memory (making sure I didn't select main memory!)
I then (as blazinazn suggested) deleted the HTC files in Application Data\HTC\Audio Manager and deteled the AudioManager_Eng.vol file.........but I deleted all the files in those folders so the playlist folder, and the AS_MediaList.db and DIDN'T SOFT RESET (I think this is important)
I then connected the phone to my PC and made a folder called "Music" on my card and just copied the music from my PC across.
I then soft resetted my phone went to the Music tab in TouchFlo (after about 30 seconds, all the songs (with album covers, thanks to MP3tag) showed up!
I didn't use Media Player, update the library or anything. I just did those few steps and it worked.
I hope this helps and thanks to you guys for your suggestions and patience.
Merry Boxing Day