My friend’s Facebook account has been impersonated. What is the best way to resolve this issue?
The first step is to contain the damage. Go to https://www.facebook.com/hacked. There, do all the steps, change password, enable two-factor authentication with your phone.
Then, think how that happened. If you don’t, it might happen again. For example, you might have clicked bad links, or used the same/simple password for Facebook and other websites. A good place to start is to look at what happened with the account. Did it post spam, or something? Maybe you gave some app permissions to post on your behalf.
The last thing to do is to observe. If it happens again, go through the steps above, and get someone good with IT help you out. Most likely, you are doing something unsafe - even without knowing.