I checked the service manual for Lenovo G560. If you flip the laptop right side adjacent to the battery is Hard Drive location and the Heatsink/Fans as well. If you are referring to this location, the issue could be an overheating which will cause your computer to randomly shut down/restart. Please try to clean the air vents as well as the fan using a can of the compressed air. If you are doing it yourself (not taking any technician's help) please go through the Service Manual on Page Number 41.
Note: Please go through the "Safety information" section of the Service Manual on Page Number 1 before you open the chassis.
You can find the Service Manual from the below mentioned link: