Are you attached to the internet? Haha, seriously though, are you?
Assuming you have the ideal login email as well as password (as well as you're linked to the internet) there's a few points that might be causing your issues:
Facebook Login Not Working
Are you obtaining a mistake message? If so, inspect the Facebook help page for explanations and fixes to recognized problems.
See to it you don't have any type of expansions or antivirus programs running that are blocking Facebook.
Have you attempted clearing the application's cache? Go to Setups > Applications > Facebook > Clear Cache. If this does not work you can try cleaning data too and as a last resource uninstalling and also re-installing the application totally.
Did you register with your phone number? Ensure you enter the country code as well when logging in.
If the application is telling you to update your email address, this is most likely because your e-mail server is classifying your Facebook emails as spam.
If you have actually just recently enrolled in Facebook you might need to confirm your account first. If you've recently altered your password, make certain you're attempting to visit with the new password and not the old one.
If you're visiting using a browser, see to it you have cookies enabled which facebook.com is contributed to your listing of safe sites.
Make certain you have the most current variation of the Facebook app for Android.
