Your issue here seems to be only resolved with facebook admins.
You were either:
1. Blocked for some reason by facebook admin staff. (contact facebook help/support via email)
2. Hacked from someone who changed your password. (contact facebook help/support via email)
3. Locked your account by forgetting your password and entering it wrong too many times. (In this case, just follow the on-screen instructions on how to re-set your account etc via your registered email on facebook and/or answering your secret questions appropriately). If you dont remember your secret question/answer etc. please contact facebook help/support.
To access Facebook help/support for these kind of issues: Go to the bottom right-hand corner of the initial facebook screen, there is a help button.Here you can search for the relevant info.
To contact Facebook help/support directly: You have to be able to login to your account, so try and convince someone to "Report issue" via his account. Alternatively what I was able to track is that facebook emails are ending like this: @facebookmail.com (but no contact info can be found anywhere).
Let me know how that went.
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