If my fb account is hacked .... than how what could i do?

[Dipanshu]

I want permanently to be safe

[Ashok]

Facebook send you email about it, and provide you a chance to change password. When you are changing password select option :Log out from all devices: and you are safe.

To make your Fb account safe , Never fill you security question and always use 0 in password 2 or 3 times. Its hard to crack password having 0 digit.

Or

You can choose patter like *Digit,alphabets,Symbols* , it's hard to break such a combination.