Only One Side Seems To Play

I use a Sandisk Sansa Clip 4GB and it seems something has messed up my Earphones Jack. Everytime I try listening to it with my Earphones, the sides switch back and fourth. I dunno how to describe it exactly. Lets just say the Earphones do not work properly on it. I checked out the Earphones and its not those. Its the Device. And the little logo for the Volume/Eaphones (I think thats what it was.) that was on the top left of the screen is gone. I am not sure if this is fixable or not. I would like to get some help on this. It would be appreciated. Thanks!

Perhaps seemingly silly to ask, but:  is the headphone jack pushed in all the way?  It can be a very tite fit, at first.