NAudio is an open source .NET audio library that can play back WAV, MP3, WMA, AAC and AIFF files, making use of ACM or Media Foundation codecs installed on your computer for decompression purposes. For ogg support, there is an add-on nuget package you can use.
(Edit: updated with details of supported audio file types in NAudio 1.7.
Also, full disclosure: I am the author of this library)