Are you connected to the net? Haha, seriously though, are you?
Assuming you have the ideal login email and also password (and you're connected to the web) there's a few points that might be triggering your troubles:
Cannot Log Into Facebook
Are you obtaining an error message? If so, examine the Facebook help page for explanations and fixes to recognized problems.
Make sure you don't have any type of extensions or antivirus programs running that are obstructing Facebook.
Have you tried clearing the app's cache? Go to Settings > Applications > Facebook > Clear Cache. If this doesn't function you can attempt cleaning data as well and also as a last option uninstalling as well as re-installing the app totally.
Did you join your telephone number? Ensure you enter the country code also when logging in.
If the application is informing you to upgrade your email address, this is probably since your email server is classifying your Facebook e-mails as spam.
If you've recently registered for Facebook you might need to confirm your account first. If you have actually lately transformed your password, see to it you're trying to visit with the new password and also not the old one.
If you're logging in through an internet browser, make sure you have cookies allowed which facebook.com is included in your checklist of secure sites.
Make certain you have the most current version of the Facebook app for Android.