Windows xp and possible drives recognized

Hi,
I was trying to fix a problem on my friend's computer (windows xp) and I managed to pull up a list of possible drive letters that windows would recognize. For some reason unknown to me now, I unchecked the g drive. This has led to various complications that i have been unable to solve through Disk Management. I tried to use the change drive letter/path to restore the G drive, but it did not work. There are a couple of plug and play devices that are having problems now (i guess they showed up as g before). I fixed some of them by changing the drive letter assigned to them, but there are still some problems. Any idea where or how I may have pulled up the intial list?
Thanks.

 

I've attached a screenshot of Disk Management below. Right click in any of the areas I've circled in red to access changing of drive letters. You may need to go into the device manager and remove all the devices that have been assigned drive letters, reboot, and let Windows re-assign letters to all these devices....