Article from Torrent Freak States that Fmovies is offline most likely due to "Legal Reasons" Although we have not heard confirmation from the Fmovies team.

Fmovies has been one of the largest streaming sites since 2016. Early on they were targeted and actually lost a case for over 200,000 in damages in US courts. 

My initial thoughts is Fmovies will be gone for good, we will probably see mirrored sites and copycats for the foreseeable future.