Do you mean https://support.avast.com/index.php?_m=knowledgebase&_a=viewarticle&kbarticleid=580 ?
Or run a command line as admin:
net stop winmgmt
del C:\WINDOWS\system32\wbem\Repository
net start winmgmt (or boot)
What did you do? What is off/on WMI for you?