Is my iphone 5 battery dead?

Hi, i have a problem with my iphone 5.
I can't charge it whatsoever. I tried different wall sockets and all that it just don't charge. The usb is not the problem because when my iphone is turned off and i plug the usb it opens the iphone but it won't charge it.
I managed to fix it twice by turning the phone off and changing the wall sockets but it gets really frustrating doing that over and over again and right now i can't even do it anymore.
So is there anything i can do to my iphone or is this a sign of a dead battery?

Maybe the charger is fubar, or the female on the phone isn't making proper contact with the male end of the plug. Someone isn't playing well with others

If your phone is still on and its not dead, try holding down both the power (sleep) button and home button until it restarts. This is called a hard reboot (I think haha) and it just restarts your phone and makes sure everything is working properly. If it isn't it will most likely fix it. If none of this works try getting a new cord and wall port (the box you plug into the wall).