If the file was working yesterday but is gone today, your antivirus likely snatched it.
For a visual walkthrough on manually replacing missing DLL files and identifying your system architecture, check out this guide: steam_api64.dll Missing Error | How to Fix | 2 Fixes | 2021 STS Tutorial YouTube• 23 Jun 2021 ⚠️ Important Warning: Avoid "DLL Download" Sites steam-api.dll for resident evil 6
The only safe source for steam_api.dll for any Steam game is via the file verification process described above. If the file was working yesterday but is