My iPhone 5 won't charge! Help!

I have a iPhone 5 and this morning i upgraded it from iOS 6 to iOS 7. When the battery was low, i had to put it on charge. After 2 hours i checked bu it was still switched off. Before my battery died, i put the charger in and it said "This cable is not certified".
How do I fix this?

Go to a apple shop.
or buy a new charger.