To save power, the computer screen will switch off (go black). Firstly, move the mouse or press a key on the keyboard. This should switch the screen back on.
If the screen remains black, please check that the computer is switched on. Is the power button on the computer on? If not, switch it on.
Check that the switch at the wall plug is on and that the power plug is properly plugged in.
If these things have been checked and are in place, then call MyZone Support.