Very typically, monitor power issues are connected to the power cable itself. Sometimes we see that office cleaning crews can wiggle the power cable free from it's electrical outlet, so make sure it is plugged in firmly. Trace the cable back to the monitor and make sure it is plugged into the correct slot.
If the power cable is plugged in securely, you can try a different electrical device in the same outlet, to make sure there is power at the plug.
If the above steps have been followed to no avail, the monitor could be due for replacement. It is best to put a support ticket in at this point to have a technician assess the situation.