How to retrieve your Facebook password on computer when you forget it
Step 1: Click on “Forgotten password?” to start.
Step 2: Enter your email ID, phone number, username or your other name that you used to use to register your account, and then click “Search”.
Step 3: Select the line “Email me a link to reset my password”, click “Continue”.
Step 4: Log in your Gmail account to receive a verification code which contains 6 numbers, and then enter to the square as below. Click "Continue".
Note: In case you don’t get any verification code, click on “Didn’t get a code?” to request again.
Step 5: Enter your "New password".
Note: The password must be strong enough, containing upper and lowercase letters, and numbers.
Step 6: Check in either of the two options. Both are good, but it is better that you click on “Log out of other devices” and then “Continue” to finish.