My hard disc changed from G to H how can i change it back on WIN7?

To change your hard drive letter back from H to G in Windows 7, open the Disk Management tool by right-clicking on "Computer" and selecting "Manage," then click on "Disk Management." Right-click on the drive currently labeled as H, select "Change Drive Letter and Paths," and then click "Change." Choose the letter G from the dropdown menu and confirm your selection. If G is already in use, you may need to change the letter of the existing drive first before reassigning G to your desired drive.