Windows 10

That is why I don't put a pass word on my pc. That happened to me and even HP would not help me get in. I think the thought is it might have been stolen. Sorry I can't help you. I don't know what I did to get in, just kept fooling around trying to get in I guess.

How far can you get only you can restart and have you tried CTRL +ALT+DEL which will bring up a screen where you can do a factory reset

Lani said:

Help
I started the windows 10 upgrade
Its at the part when it wants my password but every time I put it in & click next it acts like its loading but then does nothing..
I cannot access my compurer at all..

Did you use a MS E-mail account to login with or a normal local account?

In any case, see here:

See this Tutorial by Dinesh: User Account Password - Change from WinRE System Repair Disc.

Basically you enable the hidden Administrator account from WinRE then boot normally, click on the Magnifier which opens a Command Prompt. You enable Administrator then reboot, login as Administrator and fix the password on your other account.

Put things back when done.

Sounds complicated but isn't. Just take it one step at a time.

Turn off the computer using the power button.
Reboot and see if it rolls back to the previous OS. If not drop power again.
May have to do this 3 times but eventually it will roll back to Windows 7 or 8 that you started with.

Hmmm, some possible fixes for the black screen here: Solved Fix for windows 10 booting to a black screen - Windows 10 Forums