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Some suggestions to try. I had a 5s do this to me. Would not show it was charging, I tried a different cable first. Then try a different charger. Eliminate one thing at a time. try plugging into a computer, then try a wall charger. If none of this works, leave it plugged into a wall charger for several hours to a day. I left mine plugged in for 24 hours and it came back to life. I have never had a problem with it since.
If none of this works then it could possibly be a battery issue and you should make an appointment to have it looked at.