If you already check power/connection to the monitor, try
Ctrl+Alt+Del and see if the computer and/or monitor wake
up.
Try warm reboot or if necessary, cold reboot.
BTW, you posted to the wrong newsgroup. This newsgroup is
for Microsoft Access, a database application.
Try the appropriate newsgroup (windows server) if the
above doesn't work.
HTH
Van T. Dinh
MVP (Access)