Avast Won't Open? 7 Troubleshooting Tips To Fix Avast UI Issue! 7 Effective Methods to Fix Avast won't Open. Method 1: Repair the Avast Antivirus Software. Method 2: Restart Avast Antivirus Services. Method 3: Try a Clean Installation. Method 4: Update Your Avast Antivirus Software. Method 5: Disable the Avast Shields Control to Fix Windows 10 Action Center Doesn't Recognize Avast.