i've actually done it a couple of times. 3 actually. the first time, i thought i had a different directory selected and hit the delete key and since it was so big it asked if i really wanted to delete it instead of putting it in the recycle bin. i said yes because i still thought it was the other directory. that was probably 15 or so gigs.
the second was not that long after it and it was the same thing but that was less than 10 gigs i believe.

this time, i had a new drive in my computer i was gonna format at put in my xbox so i used a certain program to get a drive ready for an xbox but selected the wrong drive.

mistakes happen. i think it's good since i didn't listen to a lot of the stuff i had, so now i can start over with better music.