Wow. so frustrating. I just fixed this. When I booted up Windows it asked me for a password, Ok. Entered password. Windows seems to be signing me in. Nope. Black screen...just a cursor. no desk top no icons no menus...nothing, just Purgatory. After some messing around I get the task manager by hitting Control+Alt+Delete.
Ok, finally something! This is after an hour of trying to get into safe mode by trying various F keys. By the way F2 on a Lenovo laptop gets you into Bios.
So from task manager I hit "File", then "Run new task"
I googled a bit then decided on "cmd.exe" I also had to click "Create this task with administrative priviliges"
Ok good, I got a command window. Finally a way to boss this box around! First thing I ran was "Chkdsk" No problems according to check disk utility.
"rstrui.exe" was my next try. This brought up the graphic System Restore wizard. I picked a system restore point and all was well again.
I am back from Purgatory. I hope this helps someone out of the black screen with nothing to click on. Set a system restore point if you have not done so already. Its worth the time.