Something is not working. You should, before you disconnect power, rock the power switch on the front to off, but normally unplugging and plugging power back in should not cause a problem.

Maybe you should rock the power again if you have not done it, off then back on. Do you have 2 green power lights when power rocker in up (on)? Look at the processor card inside the cabinet (far left card) Do you see at least 1 LED steady blinking red? (Not the connections near the network card of you have a cable plugged in). If it is not blinking then it just tells you what you already know, that the system is not working.