This might be a wrong forum to ask, or then again not:
A retired lady just called, that she had upgraded to Win10 without a hitch. Then suddenly her desktop images started to vanish one by one. Also her pictures disappeared, but through Explorer she managed to find Picasa which could locate all of them. Also she got a message about a file in C:\ either being corrupt or moved. So she shut the computer down, hoping it would fix the problems. It didn't. At next boot the desktop was totally black with only the volume slider and Recycle bin on it, and the Start button in the corner. When she tried to open Explorer, a chat window with a woman's image popped up, asking for ransom money in Russian language. Oh, and the anti-virus program says all is fine...
This is all I know about it at this moment, I've not seen the computer yet.
Aside of asking for further information about how to fix this issue, I want to spread the information about this threat. It appears that Windows 10 isn't immune for this kind of threats, or could it be that Win10 has a brand new security hole allowing this?
So if you find your desktop icons disappear, at least disconnect it immediately off the Internet. I don't know whether the missing files have been hidden and moved inside the computer's hard disk as was the case in a virus a few years ago, or have they been uploaded to an unknown server. In the latter case there's not much to do to save the lost files, even paying the ransom won't likely help.