If you are intending to restore your laptop to how it was when you received as from factory with no user data you can use the recovery image that should be pre-loaded on your Lenovo G570.
To access and use this recovery image refer to the following link on how to use Lenovo OneKey Recovery:
https://support.lenovo.com/au/en/videos/ht051298
If the windows have been upgraded to Windows 10 or re-installed before you will need to manually reinstall windows as the recovery partition is most likely wiped on the drive.
If you are talking about resetting the BIOS settings instead you select Load Optimised Defaults in the BIOS menu last tab. To access BIOS I think it's either CTRL+S, Enter, ESC or F1.