AVRT.dll is a native library file for Windows operating system which is available since Windows 2000. The purpose of this file is to execute the Multimedia Real-time Runtime service for Windows shell common library file and the Hardware abstract layer library file. It usually resides in the C:\Windows\System32. Absence of this file can cause various errors in system.
AVRT.dll is tied with Windows multimedia services. So the user might not be able to play movies, audio, videos in Windows media player, if the AVRT.dll is not functioning as expected. Skype application might not function as expected, especially when the Cam is switched on. Windows audio service might also not render the sound through the speaker or the headphones.