MyMPx.org - Deleted ROOT File

HELP!! Was transfering music to my daughters MP4 player and when it was full I wanted to delete some but click on delete all instead. Instructions tell you how to delete all but state thta only files in that particular folder will be deleted... not so!! It wiped clean her mp4!!

It still turns on but the Root File has gone, all files now say 'empty disk" or 'disk error' except for the radio, games & tel book and I cant get the computer to recognise it at all! I found a thread from someone who'd had the exact same problem but he then discovered he could format it and all was fixed.. SO excited at a possible fix I too attempted to format her MP4 only to get 'does not support this type disk'

My daughters in tears and I'm stumped as to what to do!! :(

HELP