I believe your computer may have viruses, adware, trojan maybe. You need to remove virus from pc in order to make it fast. Else you can just reset you pc settings, your personal files will not be deleted. Only the settings would be set to default and all the apps would be flushed. Or you can run Malwarebytes in order to remove viruses or adwares. If there is no virus then simple install an SSD to make the laptop 5 times fast then it is now.