Are you linked to the web? Haha, seriously however, are you?
Assuming you have the best login e-mail as well as password (and you're connected to the web) there's a couple of points that may be causing your problems:
I Can't Log Into Facebook
Are you obtaining a mistake message? If so, check the Facebook help page for descriptions and fixes to well-known concerns.
See to it you don't have any extensions or antivirus programs running that are blocking Facebook.
Have you tried getting rid of the application's cache? Most likely to Settings > Applications > Facebook > Clear Cache. If this doesn't function you can try cleaning data too and also as a last resource uninstalling and re-installing the application entirely.
Did you register with your phone number? Ensure you type in the country code as well when logging in.
If the application is telling you to upgrade your email address, this is probably due to the fact that your email server is labeling your Facebook e-mails as spam.
If you've just recently signed up for Facebook you may require to verify your account first. If you've just recently transformed your password, ensure you're attempting to log in with the brand-new password as well as not the old one.
If you're logging in by means of an internet browser, make sure you have cookies enabled which facebook.com is included in your checklist of safe sites.
Make certain you have the most current variation of the Facebook app for Android.