iPhone 5 : USB Power adapter stopped working.

Hi,

Yesterday my iPhone was charging through the USB power adapter.

Since i wanted to use my phone i tried to unplug the charger from my iPhone when the power supply was still on, as soon as i did that a spark came off from the power adapter.

After which my iPhone is not getting charged through this USB Power adapter anymore.

What could be done now, please suggest.

Thanks !

P.S - The phone is still in warranty.