Pygame cannot open sound file

You cannot use pygames' library's unless you initialize either the modules your using or all of pygame.

    pygame.mixer.pre_init(44100, 16, 2, 4096) #frequency, size, channels, buffersize
    pygame.init() #turn all of pygame on.

do these before you do anything in pygame. I recommend it.

Pygame (version 2.9 at least) doesn't support 32-bit float WAVs. Re-encode it to a signed 16-bit WAV (using Audacity for example).