Welcome to Justanswer.com, my name is Dustin.I'm sorry to hear about the issue you are having, I will do my best to help you resolve it.
To get started, I need to know what type of computer you are using, a Windows XP, Vista, Windows 7, Windows 8, or Windows 10?
Also, when you try to sign in does it show any other potential user accounts you could use, or just the one account?
Understood.. and we can repair that computer without it having internet access.
When you return, I need to know if it shows any other user accounts when you go to sign in?
Also, does that computer have files you need to save on it or is the main concern getting it running again?