We quite often get inquiries regarding the iPhone not charging. This is very annoying for the user as obviously they cannot use their phone.
Things to try first.
1 Do a soft reset on the phone. This is accomplished by simultaneously holding down the on off button and the home button for a count of 10 seconds while the device is plugged into a charger. You may see the charging symbol appear and then the iPhone will power once sufficiently charged.
2. Try different chargers. Sometimes the fault is with the charger or cable itself. Maybe check your charger on a different iPhone or use a charger that you know works with another iPhone.
If neither of these tips do the trick then you may have a problem with either your battery or, more likely the charging port.
The Charging Lightning port on an iPhone gets a lot of use. Over a period of time the connector pins inside the port start to wear out, get corroded or the port entrance size increases  so that the USB Cable is loose when plugged into the charging port
We Fix can diagnose the fault for you if you bring it into our shop. We will connect a new charging port and see if the phone charges and boots up. If it does not show signs of charging then we will try a new battery. If neither of these methods work then there is a fault on the logic board and the iPhone will need to be passed over to our engineer for further diagnoses.
We Fix offers a No Fix, No Fee service