i would say there is no signal getting to your monitor, check the cabling and check what source is being used on the monitor usually looks like a suqare with an arrow pointing into it.
If the computer is going to sleep / hibernating normally, then you don't have to do anything. If the computer is locking up / rebooting itself, then you have an issue that needs to be addressed.
what does it mean on my monitor HP when it goes in a sleep mood and agross the monitor it says no source in come what do i do
i means that your grapics card takes to much power for your power supply just remove it or by a stronger power supply a 450 watt will do the trick trust me i had the same problem and i just bought a new power supply for it