Can you give more information please? What OS is this on? What version of FM Server?
Have you tried using command line to shut down the database server and restart?
Sorry. I wrote that in the first version of the message, deleted it and forgot to put it back.
I'm running FM 11 Server Advanced on a Snow Leopard system (10.8.6). I don't know how to shut down the server with command line.
On OSX where the server is installed, try this: open the terminal and put in
fmsadmin stop server
it will prompt you for user/pass, this is what you normally log into the admin console with.
Likely what happened is there was a problem with the admin console, not the database server itself, and it needed to be reset, or a java update conflicted with it.
Thank you. It's working now!