Look in the trash. Many deleted audio files end up there. Find the one you want and select restore. Now the audio file is in the audio section of the media browser. From there you can bring it back into your project.
iPad 2, iPhone 5, Mac Mini
iRig Keys, iRig Mic, iRig guitar, You Rock Guitar (midi guitar) Mobile In Guitar, GarageBand, Alchemy, Sunrizer, Cubasis, Music Studio, Amplitube, Mobile POD, MultiTrack, bs-16i, SampleTank, AudioBus, AmpKit, JamUp XT, G2M
Epiphone Les Paul Special GT
Music For iPad