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If you are looking at the sign in screen, you should see SIGN IN OPTIONS and under that, there is an image with 10 dots. If you click on that icon, it will let you enter your PIN instead of a password.
I have not heard back from you in a while -- If the issue is resolved, please rate our session as 3 stars or more and press Submit so I am credited with helping you otherwise please reply back so we can continue with the issue.
It sounds like the person/company that repaired your computer, setup login information if it was not there before. Are you able to reach out to that person/company again because the reset process is complicated and requires a lot of hands-on work.