Why has my lightning iPhone lead stopped charging my iPhone

I think your only option is to get one sold in Apple stores. I have a small 30-pin-to-Lightning adapter (not a cable) and it does not work with either my iPad mini or my wife's iPhone 5. I also have a non-Apple Lightning charging cable (as a backup, just in case...). Same deal.

Check lightning cable with another phone and your phone with another lightning cable to figure out whichone is faulty!

Yes! You can use your old chargers with the iPhone 5 however you will need to buy the adapter for them so that they will be compatible with the new "lightning" sync connection. You can read about it here: http://store.apple.com/us/product/MD823ZM/A/lightning-to-30-pin-adapter?fnode=48

Once you purchase the iphone,dont use it yet.Instead of using it right away,kindly charge your IPhone with the wall charger for 3 hrs.Please dont use the Iphone while charging.Kindly check always if the battery is full.Once its fully charged then that's the time that you can use the iPhone. Once fully charged, let the iPhone's battery fully drain.Please keep the iPhone off for 2 hours.Fully charge your iPhone and allow the battery to rest in the fully charged state for two hours. (You may use your iPhone during this time as long as the iPhone is plugged in).Repeat the third and fourth step a maximum of three times if you feel your battery indicator is inaccurate.

Here are some tips for your everyday charging for your IPhone:
#1 - Charge your iPhone throughout the day when available. Charge EVERY night, regardless of charge level. This will keep your battery active, which is healthy for the iPhone's battery.
#2 - Use a wall charger or car charger w/ rated output 5V 1A. Computer chargers might not charge when the computer is in standby mode.
#3 - You cannot overcharge your iPhone. You don't need to disconnect the iPhone from the charger after it's done charging. Once fully charged, the iPhone will run strictly off of AC power and will not damage the battery.
#4 - Every two months, make sure you fully charge and fully drain the battery, in one cycle. This calibrates your battery indicator. If you fail to do this, your indicator will become inaccurate. Calibrating your battery does not improve battery life.
#5 - If you ever need to store your iPhone for any reason, make sure your battery is stored @ roughly 50% and in a cool environment.
#6 - Always charge your iPhone out of its case (assuming you can easily remove the case). Charging your iPhone inside your case will make the iPhone hotter, which is bad for the battery.
#7 - Charge your iPhone in a cool location. Charging your iPhone in a cool environment has a tremendous impact on your battery's lifespan. The colder the location you use to charge, the more charging cycles you can complete without your battery deteriorating. Avoid charging in direct sunlight.
#8 - Use properly rated chargers. Using chargers that are not properly rated will have a huge impact on your battery's lifespan. Make sure your car charger has the same rating as the official Apple charger.
The official Apple wall charger is rated as follows:
Input: 100 240V ~ 50/60 Hz 1.0A
Output: 5V 1A
Thanks!

http://support.apple.com/kb/HT1808