Have the services stopped? what do you mean completely gone?Did you delete the software? You may want to provide a bit more information for a better response.
I upgraded my server from 2003>2008. Upon reboot, the service called ""3CX PhoneSystem Database Server" simply isn't there. All the other 3cx services are there.
Hmm.. first suggestion.. uninstall and reinstall, using your backup. I have a scheduled task which runs the backup nightly.. I would suggest doing something similar.
Second suggestion.. try running the app directly to see if it can come up.. using a Command Prompt window in admin mode.
Your paths may vary.. also depends on the version of 3CX..
If that works.. keep the command prompt running to keep the database running.
You can then reregister the windows service.. appears that SC still lives in Windows 7 (it's been a while since I've used it.. last time was to set up dependencies for a chain of services.. on 2003..).. http://support.microsoft.com/kb/251192 can give guidance.
Whenever you upgrade a server always backup and restore the config, 2003 isnt supported on V11 I've had really weird issues on the on occasion had V11 on a 2003 machine.... But it doesnt mean you will I wouldnt use an unsupported os
I would do the OS first.. the 3CX upgrade is more trivial.
Consider Windows 7, still running fine through v12SP1, though we did lose IIS ability in v12.. unclear why. I'm not all that fond of Abyss.. but I'm not all that fond of paying for a Server OS for a PBX, either.
Unless a client has a server on site and server os I always roll out a client on either windows 7, and on some occasions SBS as a server OS willl be more reilable but that was for more testing purposes. I've had a lot of success with Windows 7 maybe 30-40 systems on windows 7 and XP.