first of all I do not and never had a fb account so I am assuming there is an email account associated with your fb account. If so, change the password on that account. Also if there are any security questions on fb, change those also. There is really no way to find out who or how your account was changed but you will need to make changes to all avenues of accessing your account.
When I first turned on my computer for the day on Sat at about 12:55 pm and attempted to log on to one of my 2 facebook accounts by clicking into fb from a notification in my Yahoo inbox, my password did not work.
I refreshed the page and tried again being careful to not make any mistakes.
FB said the password did not match and that someone changed my password from THIS computer at 12:11pm!
My computer was turned off as I was still in bed at that time!
It also said my yahoo email address was not associated with my fb profile account!
I was able to check 'forgot my password' and they sent a message to my yahoo inbox ( the same one that was not supposedly associated with the this fb profile) .
I was able to create a new password and log in successfully to my fb account.
I ran my AVG 2015 scan...no problems and I ran Malware...no problems there either.
How could "someone" change my password who had no physical access to my lap top computer which was turned off?
My 2nd fb account was fine btw.

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