Laptop boots but screen is black


Dec 12, 2013
Today i installed a face recognition software on my laptop that unlocks the screen but when it finished installing I tried turning off laptop but it didnt turn off not even with the power button. So i took out the battery y puted it back in, so the laptop turns on and it has ghe lenovo booting logo and the spining wheel after that the computer screen is on but black. I need help it is a expensive computer so i cant buy i new one help