Can't log through FB

My main account has been logged out of desktop app for whatever reason and now i can't get back in through Facebook. All i get is an endless loop that takes me back to the login screen. Have tried different browsers and cleared cache...i have managed to login on my phone but that is of no use when trying to access game on my pc.

Anybody know of any fixes? Otherwise the account i've built up over 10 years is no longer. Thanks