answer:If this is a desktop pc, and you have moved it about while doing something, there is a small chance the graphics card is broken, and no signal is getting to the monitor. Some monitors are a pain in the ass to get off of standby, but in most cases, if the monitor stays blank, or saying no signal, more often than not it is damage to the cable or graphics card. Tips: Hold the power button down for 3, 5 or 10 seconds instead of a single click. Unplug it and plug it back in with the computer power off, and then try turning it on. If that don’t work, test the monitor on another computer to rule out damage to the graphics card, and try a different cable if you have that option, to see if that is the problem.