Most people tend to run Central Admin on a single server, as its usually a bit of a pain to run it load balanced. Now that is not normally an issue - that is of course until you lose the server its running on.
Try as hard as you might, you wont be able to just enable it on another server as the farm thinks its already provisioned. That means you will have to reprovision it on a different server, get Central Admin up and running on an alternative box and then take the old Central Admin application out of the farm.
There is a tool to help you with this and its good old psconfig.exe.
The trick in enabling a replacement Central Admin server is to ensure you provision with a new port, because if you don't the timer job that activates the newly provisoned server will not run, and the old Central Admin allocation will remain active leaving you with two innaccesible Central Admin applications.
So, on the new server as a precaution run:
psconfig.exe -cmd adminvs -unprovision
and then run it again to provision a new Central Admin service, ensuring you specify the replacement port number.
psconfig.exe -cmd adminvs -provision -port 8080 -windowsauthprovider onlyusentlm
You should now be able to access Central Admin on the new port, allowing you to go into Operations and delete the application for the old service. When you get the old server re-instated make sure the old application isn't still lurking.