The standard Windows installation does not contain decoders (Codecs) for FLAC and Ogg files. To play these files, download and install the latest version of OpenCodecs from here (e.g. "opencodecs_0.85.17777.exe"), using the default installer options:
You should only install codecs from trusted, authorized sources, such as the official website of the codec manufacturer, e.g. xiph.org. Be careful when you install codecs that you've found on the Internet, particularly the free codec packs that claim to include codecs from many companies, because these codec packs might include software that can damage your PC or may cause compatibility problems. If you've installed any codec packs and are having problems with the Music Player, we recommend that you remove them.