Hi. I'm David, and I'm happy to help you.
I can help you get back to using your original password. To make sure I give you the exact steps that will work for your setup, do you know if you signed in with a Microsoft account (like an Outlook or Hotmail email) or if you created a local account just for this PC?
If you aren't sure while logged in, you can check by going to "Start > Settings > Accounts > Your info". If an email address is listed right under your name, it's a Microsoft account. If it says "Local Account" instead, it's a local one.
Looking forward to your reply.