Periodically review the "Where you're logged in" section in your security settings. This will show you a list of all devices and web browsers currently logged into your account. If you see an unfamiliar desktop, you can remotely log it out with a single click.
Certain ad-blockers, privacy extensions, or script-blockers can break the Facebook login interface. Try opening an or Private Browsing window. If login works there, one of your browser extensions is causing the problem and needs to be disabled. Essential Security Practices for Desktop Users facebook login on desktop
A weak network connection can prevent the login page from communicating with Facebook's verification servers. Periodically review the "Where you're logged in" section
If you are having trouble logging in, try these common solutions: Essential Security Practices for Desktop Users A weak
Check if other websites load properly. If they do, flush your computer's DNS cache. On Windows, open Command Prompt as an administrator, type ipconfig /flushdns , and press Enter . On a Mac, open Terminal and run sudo dscacheutil -flushcache; sudo killall -HUP mDNSResponder . Enhancing Security for Facebook on Desktop
Enable these in Security and Login > Get alerts about unrecognized logins . You’ll be notified whenever someone logs into your account from a new desktop browser or device.