1. Conversion of fla (.flac) audio to wav audio
You can convert FLAC compressed audio files back to WAV PCM sound file format using many current audio converters available on the market. WAV files are not compressed, and as such will have much larger file size.
2. Exporting sounds from fla (Adobe Flash projects)
It may also be possible that you were trying to export some kind of audio files from Adobe Flash *.fla files. In this case you have to look for some kind of Flash/SWF editor if you don't want to use Adobe Flash. Look for flash extractor, flash decompiler, not a multimedia converter.