Here is a short essay on that topic.
(Good, but with minor frustrations)
This comprehensive guide covers everything you need to know about navigating the Facebook desktop login process, resolving common access errors, and securing your account against unauthorized entry. How to Log In to Facebook on a Desktop Browser facebook com desktop login
To ensure you are logging in safely and correctly:
If Facebook rejects your credentials, do not repeatedly guess, as this can trigger a temporary account lock. Here is a short essay on that topic
Passwords are case-sensitive. Ensure your Caps Lock key is turned off.
This is the #1 complaint.
Click the "Forgot password?" link on the facebook.com/login page. Facebook will guide you through a process to regain access to your account, which typically involves sending a reset link to your linked email or phone number.
If you use a school, work, or library computer, always: Passwords are case-sensitive