This seems to be a case that would be better handled in a TAC case.
To start, check System -> Status, are any of the processes in a red (down) state? Also check the System -> Performance to make sure the AMP server itself is in a good state (not hitting swap, disk I/O levels).
Check for crashes in the following logs:
/var/log/error.log
/var/log/visualrf/visualrf.log
/var/log/service_watcher <- watch for services repeatedly starting over
If you're not seeing anything in the logs (or if logs aren't even updating at all), then there could be a lock on the system. Try doing a 'Restart AMP' from the bottom of the System -> Status page. If this doesn't successfully bring your AMP back to life, then a web session with TAC will be the next quickest way to diagnose and resolve this.