There’s nothing worse than that stomach-sickening feeling you get when you realize you accidentally erased a critical file from a disk. Fortunately, you have a complete backup of all your files that you can use to restore it. (You do have one, right?)
If you’ve erased the file with a “secure” method, which overwrites the erased data with other data, you may be out of luck. But if you’ve done a simple “drag it to the trash and empty it,” the file(s) may be recoverable. There are a number of freeware and commercial software apps that are able to recover files that were deleted from a drive – Google “data recovery” or “recover erased file” to find some possibilities.
If you’ve lost a lot of valuable data, there are also services that will try to recover the files for you.