Windows 10 won't let me sign in

try booting in safe mode, hold f8 when screen bootup shows

F8 is disabled by default in Windows 10.

i work in I.T if anyone is having this problem still let me know i will be glad to guide you through the process -
basically for you that upgraded the account will show you its there but it been moved to the default.migrated directory hence the password has been renamed in the registry with the extenstion .bak, and by default command prompt is not elevated when you try to use net user to activate the admin account, in a nut shell download the appropiate iso windows ten from microsoft website make sure you have the right one if you are not sure i can explain that also , you will have to use the windows ten iso to get into command prompt and then if you are succesful in doing that use net user administrator /active:yes and press enter then type net user administrator 123456 the 123456 is the password you are giving the account if all is fine it will say command completed succesfully, reboot your pc and login with the password you set for the admin account , go to control panel account and user safety and select your user account from there and change the password when you reboot the pc after changing it you should be able to login if this does not work for you i can explain how to access the registry to change it there .. thanks :)
Neo checking out for now - any questions i will be glad to get you through this frustrating problem :)
jut remember the MATRIX has you - lol

OK, long dead thread, but I had this problem today and I found something nobody mentioned. Here it is, in the hopes that it will help someone.

My wife bought a new laptop yesterday with Win10 installed. She set up her user account and we started installing things last night. This morning, she couldn't log in, even though she was sure she had the right password. None of the suggestions I found in this thread or elsewhere worked. I eventually gave up and did a Windows System Reset, wiping out all of last night's work and giving her a fresh start. We set up her account. Then, having been burned, we logged out. Sure enough, we couldn't get back in for anything. System Reset #2.

So when entering the password for her account on the third (and final, or this sucker's going back to the store!), I decided to press the eyeball in the password field just to make sure the characters and cases and so on were all correct. Well, they almost were. Almost.

Windows 10, at least the version we have, truncated the password at 20 characters. We didn't notice the first two times through. Her old computer allowed the password we were trying to use, but maybe we got around the limit because that computer was an upgrade from Windows 7. I don't know, and I'm not going to mess with our current success.

So if you can't get in, try entering just the first 20 characters of your password. That's what worked for me.

My computer does a weird thing that I have to click several times to have the password bar show up. But now the password bar doesn't show up and I can't use the finger scanner either because the bar has to show up to do the scanner. It works after I restart it but don't want to restart everytime I wake up from hibernation.

Welcome to TenForums @bncase

Try opening Device Manager. Look at the details for each of the devices involved (like your finger scanner) and see if they have a Power Management tab. I found the only way I could get my WiFi to reconnect after waking from hibernation was to turn ON 'Allow the computer to turn off this device to save power' (not the most obvious solution, but it seems to remind windows to reset it when waking up).

Try yours with it on and with it off, see if one of them helps.

what else do I change because turning the finger scanner on and off didn't work. It is the password bar that is the problem, I can't get it to show up

nobody has an answer??

can you at least tell me how to never ask for a password? I put require signin as "never" but it still makes me sign in and doesn't let me. I can't stand windows when it doesn't do what you command it to do!! on many things