I am unable to see the sign-in prompt
Even though you can not see the text box type in your password/pin anyway. If it is a password, select ENTER (A pin should log you in without enter)
Everything will be too big on the screen so see if resetting graphics will work to make things smaller so you can change scale.
press the Windows key + Ctrl + Shift + B simultaneously
If above does not work, see if you can change scale from safe mode.
Shut computer down. Hold down shift key and
keep it held while turning computer on. It should put you into recovery.
- Go to Troubleshoot > Advanced Options > Startup Settings and click Restart.
- Press 5 upon restart to enter Safe Mode.
- In Safe Mode, access Display Settings and set Scale to 100%.(if you can)
- Restart the computer normally
If neither of these options help, and no one else gives you a working solution, report back. Worse comes to worse, you can create a new local user using installation media. Scale setting is done on a user account basis.
However, if your drive is bitlocked, this can not be done unless you have your bitlocker key to unlock the drive. If you use a MS account, it should be recorded in you MS account online.
That would get you back into Windows with scale fixed but it WOULD NOT give you access to you files. If you get to this point, report back and I can tell you what you would have to do to recover your files depending on whether your files are being synced to Onedrive or not.
Another option to creating another account would be a clean install.