Inbuilt Speaker not working

Question

Action performed:Laptop was on and MP3 player Winampplayer was running with normal volume (in-build speaker was on).Observation:All of sudden sound disappeared but Winamp wasrunning without any intervention.Workaround done:

The same MP3 songs were played in Windows media player (default in build with OS). Result: No sound through in-build speaker.MP3 songs are playedwith Windows media player/Winamp, with head phone. Result: Able to listen soundwithout any problem.