I can only suggest is to Restore Factory Default Setting to remove W8 OS and re-install in a partition drive. You can check the official website of lenovo to get information or call the re-seller of lenovo laptop and ask them on how you can restore the previous OS.
Check out the drivers for Windows 8 available through the Lenovo Support pages on their Windows 8 Beta Drivers page. I have an X220 and a T520 and it's been invaluable for providing many Windows 8 capable drivers for those machines. It's a great resource for Lenovo owners running Windows 8.