Hi Nibbie. I'm Greg, an installation specialist, 10 year Windows MVP, and Volunteer Guardian Moderator here to help you.
First try to change the password which should work if you have any alternate email or phone set up to confirm your identity:
https://support.microsoft.com/en-us/help/402683...
If that fails you'll have to do Account Recovery which can take some time so it takes patience because they are protecting your property with the waiting period:
https://support.microsoft.com/en-us/help/17875/...
I hope this helps. Feel free to ask back any questions and keep me posted. If you will wait to choose if I solved your problem, I will keep working with you until it's resolved.