If you have recorded audio from the Internet and do not know the the existing format of that file then it is recommended to change the format into standard well known format such as MP3, MP4 or WMA.
Before making a change of audio format, try to open the file in your some popular mp3 player installed on your computer such as windows media player, real player or winamp. If you have downloaded the k-lite codec then the audio format will be playable on your system.
If you are unsure if your file is an audio song then check out the filename extension, for example if the file is named as myfile.midi then a Google search reveals that this is also one of the audio format which can be opened with the use of k-lite codecs.
To change the audio format of the popular Mp3, Mp4 or WMA format download any of this freeware
Check out the above audio converters and make sure the input audio song is supported by those free wares (info given on there homepage). If you want to convert wma file to mp3 then you can download tuneclone app for windows media player. If you have any other extension and want to convert them then comment on here so that I can find a suitable freeware software for you