Are you linked to the net? Haha, seriously though, are you?
Thinking you have the appropriate login email as well as password (as well as you're connected to the internet) there's a couple of things that may be causing your issues:
Facebook Sign In Problems
Are you obtaining a mistake message? If so, check the Facebook help page for descriptions and fixes to known problems.
Ensure you do not have any kind of extensions or antivirus programs running that are obstructing Facebook.
Have you attempted clearing the app's cache? Most likely to Settings > Applications > Facebook > Clear Cache. If this doesn't work you can attempt clearing information also and as a last hope uninstalling and re-installing the application totally.
Did you sign up with your telephone number? Ensure you enter the nation code as well when logging in.
If the application is telling you to update your e-mail address, this is probably due to the fact that your e-mail web server is classifying your Facebook emails as spam.
If you've recently signed up for Facebook you may need to confirm your account initially. If you have actually just recently altered your password, see to it you're attempting to visit with the new password and also not the old one.
If you're logging in by means of an internet browser, make sure you have cookies allowed which facebook.com is included in your listing of secure sites.
Ensure you have one of the most recent version of the Facebook app for Android.
