I have discovered simple step-by-step directions that allow you to install icons that have been damaged. I recently lost my icon for Mozilla Firefox and when I took the following steps, the icon was restored. You have to follow these steps exactly as set forth below:
1. Close all folder windows that are currently open.
2. Launch Task Manager using the CTRL+SHIFT+ESC key sequence, or by running taskmgr.exe.
3. In the Process tab, right-click on the Explorer.exe process and select End Process.
4. Click the End Process button when asked for confirmation.
5. From the File menu of Task Manager select New Task (Run . . .)
6. Tape CMD.EXE and click OK.
7. In the Command Prompt window, type the commands one by one, exactly as set forth below and press ENTER after each command:
DEL IconCache.db /a
8. In Task Manager, click FIle, select New Task (Run . . .)
9. Type EXPLORER.EXE and click OK.
That should do the trick and your icons should all be restored. Hope this helps.