iPhone can't connect to laptop - urgent!

Hello peeps!
I am kind of in an urgent situation - I've got some files in my iPhone that need to be immediately transferred to my laptop for processing, but I encountered this irritating issue midway. When plugging my iPhone via USB port, the laptop displayed something about insufficient energy supply but I disregarded it and proceeded. But then it didn't recognized my iPhone any more. Now the thing is whenever plugged in my iPhone is charged but does not triggered the iTunes or appear in the program list.

Please help! Thanks a lot in advance.