How to exit from Stand by

Well, you lift the lid!

But if you mean you want your computer to behave differently when you close the lid go to control panel, power options, advanced tab.

Lifting the lid does not do anything good. the screen is black!! How to get the screen back to normal.

Pressing the power button should also bring it out of standby. If it doesn't you have a problem.

As mentioned, lifting the lid should wake the machine (at least on some of the models).

Peter