We need to trace this fault to the charger , battery or phone. I would take it to a friendly local phone shop (!) and ask them to test it on their charger, see if it comes to life even briefly. alternatively if you have a 12 volt car charger try that.
batteries rarely deteriorate suddenly - they usually lose their charge more quickly than before. sudden 'death' can be the phone itself.
hopefully you just need a new charger or battery and won't have to send it away, as either of those two can be bought 'off the shelf'. i don't think there's any easy way to bet stuff off a dead phone - cross your fingers!