avast free not opening

When I start up my computer, avast works fine. But after half an hour, whenever i try to click on the avast icon on my desktop or system tray, nothing happens. I am using windows 8.1.

What exact version of avast?
Have you tried a repair?
If not do so and see if that is solving it.

The repair didnt solve it. It turned on windows defender instead

I am using avast 2015.10.0.2206

What AV did you use before avast?
did you remove it before installing avast? … if yes, how did you remove it?

I had norton 360 beforehand. I unistalled it by going into change or remove a program and than running nortons unistaller

so you did run Nortons removal tool after uninstall?

General: Uninstalling a third-party antivirus software http://www.avast.com/faq.php?article=AVKB11#artTitle

Yes

Actuaaly no i didnt. i am doing it now

OK… if still problems

go here https://forum.avast.com/index.php?topic=53253.0
scroll down to Farbar Recovery Scan Tool … run it according to instructions and attach the two diagnostic logs here

Essexboy will then have a look when he is online

Ok thanks