If these suggestions don't do the trick, it'd be helpful if you could add some additional information like the device you're having troubles logging in from or if you see any error messages when this happens.
It'd be also helpful if you could let us know if your account was created through Spotify and then connected with your Facebook profile or through Facebook directly.
Let us know how you get on! We'll be right here if you're still having troubles.
Have a lovely day :)
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"Kindness is the language which the deaf can hear and the blind can see." - Mark Twain