Valve (the creators of Steam) has sophisticated anti-tamper systems. If you attempt to modify a game's files to bypass ownership checks, Steam can detect the irregularity. This can lead to:
: Open your antivirus software and check if the steam_api.dll has been blocked. If it has, restore it and add an exception for your game folder. Manual Re-installation : steamapirajasdll best
If you encounter a file named steamapirajasdll on your system: Valve (the creators of Steam) has sophisticated anti-tamper
Check your antivirus history. It may have moved the file to quarantine immediately upon download. steamapirajasdll best