Warning: preforming these steps will result in deleting all partitions so take backup before you start.
I managed to solve the problem after a lot of Googling. And I'm sharing the solution I found with you guys.I tried to install windows 7 on Lenovo G700 . The installation process didn't go through, it keeps showing me this message :
Windows cannot be installed to this disk the selected disk is of the gpt partition style.