If you forgot your password from your Facebook account, then reset your password:
- MOBILE: Open the Facebook app → Tap ‘Log in’ → Tap ‘Forgotten password’ → Enter your mobile number or email address and tap ‘Find Account’ → Follow the on-screen instructions.
- WEB: go to https://www.facebook.com/login/identify → Type the email, mobile phone number, full name, or username associated with your account, then click ‘Search’ → Follow the on-screen instructions.
See Facebook Help Center for more information:
Fix a Login Problem https://www.facebook.com/help/283100488694834
Login and Password https://www.facebook.com/help/1573156092981768