Mouse, keyboard, monitor keeps blinking on PC start

So I turned on my PC, and my mouse, keyboard, and monitor keeps blinking at the same time. It's like a slow blinking, and they all won't react to anything... Please help me because I can't find anything online about this... I cant even unlock my pc because it wont react! BTW the pc worked just fine when I still was at a friends house, as soon as i got back home and put my pc back on my desk, it does this...