Why power adapter won't charge

I have a macbook pro 13" early 2011

Yesterday the battery went dead when i tried to charge it in the morning there was no light on the megasafe charger.

After several attempts to reset the SMC with the charger connected there was nothing responding.

I unplugged the charger pressed the battery indicator and tried an SMC reset and the laptop started for a few seconds before it reshuted dien since there's no battery even though i replugged the charger.

I should say that this happened the last time and i tried my charger on an other laptop and it worked so i thought it's a hardware problem and took the laptop to a repair shop who fixed it sating it was only a software problem.

I need to find the fix myself so that I don't have to keep paying the repair shop for the same problem.

Thanks