Actually the button is on the lower back of vacume.. I checked my answer.. it is on lower back. It should have a sticker saying " reset button "

Turn the vacume where you can see the bottom of the vacume cleaner. On one side of the bottom of the vacume cleaner there is a small hole that has a button in it. It takes some kind of small straight object like maybe the straightened clothes hanger hook to push the button on bottom of vacuum cleaner. If the motor is on and roller is not turning, check the roller belt. You may have to take the screws out of the bottom cover to check out the condition of the belt. The belt goes around the roller and goes over, ( or around) the pin , or shaft under cover.