I suppose you are working under linux. Maybe knoppix.

You did install firefox again. You installed it now in another directory. No problem.

Find where you did install it now (find / -name firefox). You will see a bunch of directories and files in that directory. They will have the same names as the directories and files in /usr/lib/firefox.

Copy the content of the new created directory to /usr/lib/firefox. It will substitute the old files. Clice in firefox and you will have the new firefox working.

Go to your desktop and right click on a empty space. A menu will shine in front you. Find the create new. Create File. Link to your program. Put a name for your program (firefox) and click in the foremos right tab and fill program and path lines. You have a icon in your desktop.

Should not be a problem to find the right figure for your icon. Firefox has many. If it is a problem I can send you the icon.

Julio Borges
Rio de Janeiro - Brazil
Running Kurumin (a Brazilian flavor of knoppix)