Do you mean that the dedicated server is
unmanaged? If so, you would need to use the hldsupdatetool to "update" your server to an older game version. To do this, shut down your server, open a command prompt window, and enter commands like this:
hldsupdatetool -game cstrike -command update -dir hldsbase
If it's a managed
server, what I said before still applies. Further, you could also run the repair yourself, through the "Managed panel" page.