I'm glad you figured it out. Here is some additional helpful information.
By default VLC Media Player can only play the audio when you have recorded with MP2L2 encoding. Hikvision has there own player caller VS Player, which you should use for video playback of recorded video. VS Player plays all the types of audio encoding, the video plays better and you have additional controls such as digital zoom, video clipping, snapshot and continuous snapshots. You can download VS Player from Hikvision's website: http://www.hikvision.com/en/us/download_more.asp?id=1130
Additionally, you need to be sure that you have selected to record "Video&Audio" in the video settings of the camera.