What should I do if I delete a file by mistake?

Bring deleted files back from the dead. When you delete a file from your PC or memory card, you're not wiping it off the actual hard drive. Instead, you're simply removing the index information that tells your PC where the file is, at which point the PC is free to treat the part of your disk that contain that file as empty space that it can write something else to. If you've accidentally deleted something, undelete utilities such as Recuva can help you find those files again as long as you haven't already written over that file with something new.