Hello Kathy, thanks for posting this in our community.
I know how annoying it is when your Surface won’t accept your Microsoft password, even after you’ve reset it and confirmed it works elsewhere. Let’s try a couple of quick fixes:
First, boot into Safe Mode with Networking. On the login screen, hold Shift and click Restart. Go to Troubleshoot > Advanced Options > Startup Settings > Restart, then choose Enable Safe Mode with Networking. Try logging in again.
Also, check if your date and time are correct. Tap the network icon on the login screen, go to Wi-Fi settings, and verify the clock. If it’s off, open Command Prompt from Troubleshoot and use the date and time commands to fix it.
If nothing works and you're okay starting fresh, you can reset your Surface from the Troubleshoot menu. Choose either keep my files or Remove everything.
Hope this helps! Let me know how it goes.
Warm regards,
John Oli