Can malware remove OS

I have a computer here that was running a little funny, mouse was disappearing so they held the power button down to shut it off. Upon restart it went into windows 8 repair but couldn't finish.
I took the computer to my place and found that windows 8 was almost completely wiped out. The "programs files" folder was missing, the "users" folder was missing, windows folder was empty.
Can malware do this?
The other question is could someone maliciously do this?

This computer runs appointment software for a salon and she's now out of business more or less (she should have been backing it up). She had 5 employees walk out the day before this happened, so we're wondering if they did something.

I cannot recover the files she needs. I ran easy recovery pro and recuva only to get corrupted files. Now I'm trying to figure out how this could have happened.

What makes this so weird is that the hard drive tests out to be good, so how did all these files disappear?

 

Thanks for your response. I ended up getting answers at bleepingcomputer.com right away. The best we could come up with is that windows was possibly doing something when the person held the power button to power down. I found hundreds of folders and thousands of files in a folder called "found.000". So her files are gone forever and her business is screwed for months.