google chrome has stopped using unity web player. you can re enable it temporarily but soon google chrome wont support it all together.All the info you need ...
Download the Unity Web Player installer file from the link above. Save the downloaded file to your computer. Double-click on the downloaded Unity Web Player installer file.
Unity Web Player is truly depreciated because better technologies are available which are more streamlined and provide better functionalities. You should consider migrating your game/content over to WebGL technologies.
How do you make WebGL in unity? To access the WebGL build settings, open the Build Settings window (File > Build Settings). When you select the Development Build. Enable the Autoconnect Profiler setting to profile your Unity WebGL content. WebGL has some additional options in the Player settings.
doc for "unity web player ie".(Page 1 of about 8 results)