When all icons looks the same but has the proper application associated with it.
In this case follow these steps.
1.Go to Start > Run.
2.Type in Cleanmgr.exe and hit enter.
3.Select your windows installation drive and click on OK.
Now you will have this window in front of you
Make sure that Thumbnails option is selected and click OK.
Now all you have to do is Log off and Log on.You're done.
In this case not only all icons looks the same but also on double clicking they all end up launching the same thing.This error occurs due to wrecked up file type association.
If you are facing a similar problem you can try the following procedure.
1.Go to the link given here and download the association for files in zip format and extract them to a specific folder.
1.Now go to Start > Run.
2.Type in Regedit and hit enter.
3.Registry Editor Window should now be in front of you.
4.Click on File > Import.
5.Browse for the .REG file in the previously mentioned folder and click on OK
the entry will be imported.
6.Repeat step 5 until all reg files have been exported successfully.
Restart your System and you're done.