It's very common feature, it's exists since long back. :)
#1 - source control, as chrisb suggests! This should be your #1 priority starting tomorrow morning!
#2 - if you reject source control for some reason, then use nightly backups
#3 - if you reject all of above, then make regular manual archives of your project suite and store them elsewhere
#4 - if you reject everything in general, you may be fortunate enough to rely on the .bak files (auto-created by the good folks at Smartbear) in the same folder as your script files.
#5 - if you have a horseshoe up your @$$, you may be able to recover a lost file using a file recovery tool such as Recuva (as your last resort).
Cheers!
