HELP ME! Avast won't start, reinstal. repair. uninstal - nothing!

Can somebody to help me, please? My avast block from the beginning, from the installation. It block, restart my PC, bug my fresh copy of windows and till then it won’t start, won’t uninstall, won’t repair - noting.
I can’t uninstall it, delete it - noting. Just stay on my system part of HDD and in my “Programs” and don’t permit to instal any security software, stops my downloads and so many else bad things. HELP Me to protect myself from this VIRUS!

1]
avast is not malware

2]
If you want help, you really need to provide more details.
What os/sp?
What exact version of avast?
Do you have any other (security) related software installed or did you?

I can't uninstall it, delete it - noting. Just stay on my system part of HDD and in my "Programs" [b]and don't permit to instal any security software, [/b]
sounds like you may already have to many security programs......