This post will help you on how to get it fixed right away.
See: Forgot your Facebook username and password? Here Is How To Fix It
1. By using associated email
This is the most common way used to reset or change the Facebook password when someone forgets their phone number associated with their account.
1. Go to Facebook and click Forgotten Password? option
2. Enter your email or mobile number or username or full name in the text box and then click Search
3. You can see three ways to reset the password. Choose the email one and click continue
4. Check your email inbox to get the recovery code
5. Enter the recovery code in the text box
Now, you can set your new password and use your Facebook account.
2. No access to the associated email
In this case, you have lost your Gmail/email password which is associated with facebook account. Follow these given steps:
1. Go to Facebook login and click Forgotten Password? option
2. Enter your email or mobile number or username or name and click Search
3. Click “No longer have access to these
4. If you had set up previously then You will be redirected to extended recovery options.
Security Question: This method is not available for new Facebook users but old users can use this. You have to answer some security questions which you have been set up.
Trusted Contacts: You can only use this option if you already have chosen some trusted contacts.
1. Enter a new email address or phone and then click Continue
2. Type the full name of your trusted contact or friend.
3. Now you can see some instructions which include special URL
4. Share this special URL to your friend which contains security code
5. Ask this security and use it to recover your account.
That is it on How To Recover Facebook Account When you forgot your phone number.