No signal?? Keyboard and mouse wont work? but it worked b4.?

Question

Well this other computer that we have has a problem.

We had to get a new monitor a while back and the one we got will work sometimes. When it doesnt it says No Signal . we fixed it then didnt use it about a month and now we just tried to add a graphics card, but now the monitor says No Signal, the keyboard and mouse will only flash once , the keyboard might stay lite but the mouse wont. all the cords are connected. It should work but wont.
What is wrong with this thing?

Answer 1

It is probably because of inactivity like a car. If it is connected but says No Signal, try unplugging it wait a few seconds and plug it back in. Other than that, I would say damage to the wires' inside.