Open Question: 3 craigs mp3 players no sound?

Yeah bought this knock off ipod but it really is crappy first time I got 1 sound didn't work maxed it out
nothing happened. Returned it 3 days later sound goes out again changed headphones just in case still nothing. Returned it again they assured me this one would work and now its out again...Anyone know what I can do to fix this? I can tell you the people at the store have no idea what to do.