ACTUALLY I got it to work, finally. I am not technical. So just use minitool partition wizard, found here:
http://download.cnet.com/Partition-Wizard-Home-Edition/3000-2094\_4-10962200.html?tag=mncol;6
- open the program, right-click on the drive you want to change
- select "change letter"
- click the drop down box by "new drive letter"
- select the letter you want to change it to
- click "ok"
- at the bottom left corner of the program click "apply"
and that's how you do it