help me if you can lol

[jimzinhere]

i recently downloaded some free software that is meant to edit file names in large batches, (file renamer)
i have a external hardrive that i use for work, i am a dj, my hardrive contained over 300 gig of music mp3,s music videos mpeg and avi, karaoke tracks in avi format i think aswell, nearly 30,000 files altogether, i wanted to put numbers at the begining (to make searching for tracks easier) but couldnt, what i did end up doing is,
editing the file names and putting numbers at the end, and possibly something else, but in doing this when i browse my files they are appearing as text files or something and not mp3 mpg avi or whatever they were before and will not play, the funny part is im meant to be flying to greece to work there for the summer in a couple of weeks and i desperatly need to fix it all lol

any one know of any software that may help or anyway of reversing what ive done, like an absolute moron i havent backed up anything whatsoever and this is gonna be a very very expensive mistake if i cant rectify it