If that checks out fine you can try re-registering with virgin mobile. To do this you'll need to go into your network settings and search for networks. Then pick one of the other networks which will fail to connect as you have a vm sim. Then do it again, this time picking vm.
If you still have problems after that, maybe you have a sim fault.
Do you have the newer (since December 2017) purple sim card, or older red one?