You will need
First of all, try to intensify the work in any way, for example, movement of the mouse. Touch the mouse and pull it in several directions. It often happens that some users are confusing standby and hibernation. If that doesn't work, press any key on keybord or press to return to the previous state Escape. It is located in the upper left corner of any standard keyboard.
Then try Ctrl + Alt + Delete. In the window that appears you can select the option "restart the computer" to return the system to a healthy state. The Power button on the keyboard can cause the same effect if this key was assigned to an appropriate action.
Otherwise it is recommended to use the button prompt your computer restarts Reset button (the smaller button). Don't worry about apps and open files you were working on, a memory dump was saved in a special file, so during computer startup everything will be restored.
If for any reason you failed to restart the computer, try unplugging the power from the motherboard. It is necessary to deploy the system unit and press the switch located near the power supply fan. After a short interval elapsed time (5-7 seconds) turn on the computer again.
It is also advised not to use sleep or standby, if you have problems when you exit hibernate mode. Just right click on a blank spot on your desktop and select "Properties".
In the opened window go to the tab "screen Saver" and press the "Power" button. Go to the tab "Hibernate" and uncheck the item "Enable hibernation".