Software update
Keep your unit updated. Get the latest updates, free of charge, to keep your device running smoothly and securely. You will need an empty USB-memory (FAT32) in order to update head units.
This is the #1 cause of this error. Antivirus software (including Windows Defender) often incorrectly flags custom or modified steam_api.dll files as malware. black ops 2 cannot create steam-api.dll
Windows may restrict Black Ops 2 from writing new files to the Program Files or steamapps directory. This is the #1 cause of this error
This is Steam's built-in tool for repairing missing or corrupted game files and is often the best first fix to try. black ops 2 cannot create steam-api.dll
Open by searching for it in your Windows taskbar.
Click Verify integrity of game files... and wait for the process to complete.