Should I change a registry file to get my game to work? Or change the directory some how?

My game is installed on a external hard drive. It used to be registered as G: on my laptop. But now it is suddenly I:

As a result my game will not run. When hitting play it says it can't find the G:/Program Files/Microsoft Games/ blah blah file. And when I click on the executable in the hard drive it says it can't locate the game elements.



So either I go into the registry and find the file and change it so it looks in the I: drive. Or I figure out how to change my external hard drive back to G:



Can anyone help? And/or explain how to do it?Should I change a registry file to get my game to work? Or change the directory some how?
Right click on the desktop icon, properties, and then where it says start in (for example) ';C:\Program Files\Microsoft Games\Halo Custom Edition';, if my c drive got renamed as D, then change it to this: ';D:\Program Files\Microsoft Games\Halo Custom Edition';



Make sense?