: Go to Settings > Downloads > Clear Cache .
: Downloading and running executable files from an unknown .rar archive is the primary way systems are compromised. How to safely repair Steam: mpn-fix-repair-steam-generic-rar
Are you seeing a in Steam that led you to look for this fix? : Go to Settings > Downloads > Clear Cache
If you are actually experiencing issues with Steam, use the official methods: mpn-fix-repair-steam-generic-rar
If you have already done so, it is highly recommended to run a full system scan with a reputable antivirus like Malwarebytes and change your Steam password immediately.