I had the same problem as the OP. Had uninstalled the MediaBrowser 3 software but wanted to install it again...
So here's what I did to get it back...
1. Connect the USB to the camera and to the computer.
2. Windows 7 has the pop up with Options to auto-play, view files etc..
so I chose to "open the folder to view the files".
IMPORTANT: Make sure to open the folder in the drive called "JVCCAM_APP" and not "JVCCAM_SD"
3. When inside the JVCCAM_APP folder, you'll see the "install.exe" file.
Double click and the software will start to install.
Hope this helps. Btw, it's new year's eve so, hope this makes someone happier for the new year!