Is it a Microsoft Account or, a Local Account?
If, it's a Microsoft Account:
On another device visit:
https://account.microsoft.com/password/reset
Enter your email address
Verify code
Create a new password
Restart your Surface
Connect to Wi-Fi on the login screen
Sign in with the new password
If you have a Local Account:
If You Set Security Questions:
At login screen, click Reset password
Answer security questions
Create new password
If You have not Set Security Questions:
At login screen hold Shift
Click Power → Restart
Choose:
Troubleshoot
Reset this PC
Select Keep my files
Follow onscreen instructions.