windows failed to start

This laptop should have a small button which should be right of the power button for the laptop.

Press that key when the laptop is off. It should kick into the Lenovo one-key recovery.

Try doing a system image recovery there to get windows working again. You may need to wipe the hard drive when prompted which you will lose data using that method.

If the recovery does not work or fail then you may have a faulty hard drive that needs to be replaced and then windows reinstalled on it again.

Edit: You should also be able to boot one key recovery by repeatedly pressing F11 after turning the computer on until you see the Boot menu option screen, select enter bios and look for one key recovery through there. Arrow keys on keyboard to navigate bios, enter key to select an item.