If you cannot start Windows, use safe mode for system restore. Restart the computer and press F8 after the beep POST. In the menu of boot options select "last known good configuration". Select a rollback point that is closest to the date when the system was stable.
You can choose how "Safe mode". On the question of continuing work in this mode, answer "No". After this should start the recovery system.
If you see the message: "system Restore failed", reboot again, press F8 and select the option "Safe mode with command prompt". Log in to the system with administrator rights. After booting enter command line code %systemroot%system32 estore strui.exe. Follow the instructions.
If the function "system Restore" is disabled on your computer, make a back up will not work. It is possible that due to incorrect operation of the computer cannot enable this option. In this case, reboot and log in safe mode with administrator rights.
Go to "control Panel" and expand the "administrative tools". Start the Services snap-in. Find the item "system restore Service" and click right button to invoke drop-down menu. Click "start".
To run this function from the command line. Apply the combination Win+R and type compmgmt.msc. Double-click on the node "Services and applications" and select component Services.
In the right part of the screen, find the item "system restore Service". Click on it with right button and select the context menu command "start".
There is another way. Call the command prompt and type cmd. In the console window type the command net start.