I suggest you to use a 3rd party library. PlaySound only can play WAVs, and is not able to play more files in the same time.
I personally use the Bass Library.
All you have to do is:
if(!BASS_Init(-1,44100,0,0,0)) //Initializes BASS Library. Needed only once.
HSTREAM AudioChannel = BASS_StreamCreateFile(false,"Audio File Name Here plox",0,0,0);
//Create a Audio Stream from a File.
//Plays the Stream.
//Waits until song/audio file ends.
This is the complete code you need to play an audio file.
BASS Library natively supports WAVs, MP3s, OGGs and has many plugins like WMA, MP4...
Other functions are:
BASS_ChannelStop(HANDLE) - Stops a Stream
BASS_ChannelPause(HANDLE) - Pauses a Stream
HANDLE is AudioChannel over. (I mean, you can do BASS_ChannelStop(AudioChannel) and BASS_ChannelPause(AudioChannel). Remember, ChannelStop stops a channel, ChannelPause pauses it and you can re-play it with BASS_ChannelPlay. )