Hard drive simply died

I been working on computer for like 20 years now. I know what to do when a drive dies and how to get your info back, if your lucky I can. I had a customer call me and told me her computer just stopped working. She had done all her updates and kept her anit-virus up to date. She is using windows 7 I took the sata drive out and installed it on another machine. The drive spun up and seemed to be working, but nothing was on the drive. I use some undeleting software and it reported that there was nothing to undelete! I used windows disk management to check the disk, said it was healthy and active. Then I found it needed to be formated. Well, couldn't figure it out, so I told her it needed a new drive and the os put back on.
Two days ago, mine did the same thing! I am running windows 7. I use the same anti-virus, I take care of my machine. No I didn't put her hard drive on my machine, I have others to check that out. But the drive is the same, nothing. All data gone! Everything seems to check out ok, just seems to be needing to be formated. I haved formated it yet. Hoping to get back the data. No I didn't back up the system.
Any ideas where to look? What to do? This a virus locked it out? Bug in windows 7? I am all out of ideas.