My son accidently set "all files" on our computer to open with 7-zip. Or at least that's what he thinks happened. Now we cannot access C drive at all. Windows tries to open but can't. It tries to run checkdisk, but checkdisk runs forever without stopping. Is there anyway to get into the computer without having to use recovery? I really don't want to lose my files. Have you ever heard of something like this happening?