Can't open disc C and D by double clicking

Hello, I'm new at here. I have this problem. I can't open my C and D drives by double clicking on them, instead the drive are beeing opened in my XnView program. But I still can open the drive by right clicking and choosing open. I tried removing the XnView folder from Program Files folder, but when I double clicked on my drive it automatically started Open With box! I've searched the web trying to find the solution I've tried many things one of theme were Disk Heal program I've downloaded it, installed it, run it and red the instruction, the first three lines sad:
"1)Fixes Disk Problems:

Fixes the "Open With" Dialog or "Could not find 'something'" error
which occurs when a drive is opened."
But when I tried to fix it nothing worked. Maybe I did something wrong with the program, maybe it wasn't programs fault after all.
On the web I found two possible reasons: 1 Anti-Virus program deleted autorun file with the virus.
2 It happened because of drives icon change @ Control Panel>Appearance and Theme>Folder Options>File Types.
Now I know it was the second one because I tried to change the drives icon(it didn't work,but in the file type wen I pressed the advance button it showed me that the icon is changed.). I changed the icon beck but still nothing. I'm telling you all this too give you as many information as possible.Ask me if you need more information! Sorry if I've confused somebody.
So that's my problem! Please HELP ME if you can! I'll be VERY grateful for any HELP! Sorry for English, I tried!