Unhappy [Q] help ! i managed to mess up my sound

downloaded and installed viper fx, a app for messing around with the sound on a galaxy s4 at&t i337 model, it asked to edit my build.prop file so i let it without having a backup do not really know much about this stuff thus far but gotta start somewhere, anyways my sound on my phone now sounds really dull and strange, wondering how im going to fix it please help