Left earphone not Working


I have a Sony Vaio VPCEH18FG with Windows 7 Pro and all the drivers are up to date. I recently bought a new earphone and it was working fine for some days. One day, the left earpiece stopped working. I then restarted the Laptop and it worked fine. Today I faced the same problem and so I restarted several times but the problem wouldn't go. I removed the earphones and tested with the internal speakers and both of them work fine.