uninstall a software badly installed

Hi
I have a problem with avast 4.8 familial edition, i installed it, it seems something happened with the download and the result is avast is not working. I wanted to uninstall it but the picture isn’t on my computer (programs and files… i search everywhere) and from panel control it doesn’ t work, the icone disapear and appear again when i delete it. I don’t know what to do because my computer isn’t under any antivirus for the moment.
Thanks for your quick answer.

Download the latest version of avast http://www.avast.com/eng/download-avast-home.html and save it to your HDD (if you didn’t do that before), somewhere you can find it again. Use that when you reinstall. Scroll down and select the avast direct download link for the French version.

Download the avast! Uninstall Utility, find it here and save it to your HDD.

    1. Now uninstall (using add remove programs, if you can’t do that start from the next step), reboot.- 2. run the avast! Uninstall Utility, reboot. If step 1 failed, as yours did it will be necessary to run this from safe mode, once complete reboot into normal mode.- 3. install the latest version, reboot.