Welcome to the forum. :slight_smile:
Step 1, try a repair: Control Panel > Programs and Features > select avast! uninstall > scroll down and run Repair > Reboot
If that doesn’t work, do a clean install. You can find step by step instructions at:
https://docs.google.com/document/d/1TCCX0R7AAF2WOxAMQ_kcun2nNnCPFAk2P4RBzFXSgds/edit?usp=sharing