The earphones are not working properly. the voice is coming only in one of the earphones not in both of them

You could try using your earphones with another device to see if they are working properly. For example, I think my earphones have a broken wire in them because when the earphone plug revolves up or down in the jack the sound cuts out. When I turn the plug around a little, the sound comes back. (I am sure you had the volume turned up :)

Hummm... can you hear ANY audio from the speaker/earphone jack on your computer?...

Try any budget earphone/earbud.

Anthony

Do the Restore factory settings.Default security code is 12345 .If it is not work you have to give to service center

The fault could be the earphone, check the earphone in a different device/player, if the fault still appears the the earphone is faulty, probably a broken wire in the cord.
If the earphone is OK then the earphone socket in the MP3 player is faulty. If may be too expensive to repair, unless you can DIY.

first check you connected the earphone properly. earphone has two wire. connect earphone green wire where you connect the speaker.

Hello Sound like you have a Mono jack output you can try some headset models that can be used Mono or Stereo.
http://www.tvps.com/Products/ECS-Deluxe-35-mm-Mono--Stereo-Over-Head-Headset---New__ECS-OH3-prd-5MSVC.aspx

http://www.tvps.com/Products/Lanier-MP-555-(425-3117)-35-mm-Dual-Speaker-Headset-with-Volume-Control---New-MP555__LA-MP-555.aspx

or if you don't like this models look for this Earbud Mono headset.
http://www.tvps.com/Products/ECS-Deluxe-DEB-35-mm-Transcription-Mono-Headset---New__ECS-DEB.aspx

The headset you are using is a stereo headset. This unit uses a mono headset. Look at the end of the headset. If there is 2 black rings, it is stereo. You can get a stereo to mono adapter at Radio Shack for about $2.50.

THE RIGHT SPEAKER OF YOUR EARPHONE HAVE TO BE CHANGED

Try change the earhone, at least test with a another or a new one, they often break the wires and connections near Jack.

one side of any earphones (we've checked and it isn't the earphones) doesn't work. It does work if you press down on the plug in or hold it to one side.