Computer no signal from monitor

Hello,



tried a solution of the unplug and hold down and all this wth the power cable and on button, frst tme ths worked and was really please but i acc moved my pc to fast and screwed up agan, tried what did frst tme but ddnt work, thnk just got lucky the frst tme and lookng for someone to explan the holdng button and takng power cable thng n proper detal cause know t works dont want anythng else unless its easy

thanks