accesories may not be supported. Please fix this

Did you already try to reset the phone by holding the sleep and home button for about 10sec, until the Apple logo comes back again?

You will not lose data by resetting.

I assume you have already checked the docking port and the plug for any kind of debris or lint?

Maybe check this article as well:

If you need help with iPhone, iPad, or iPod touch accessories - Apple Support

Did you already try to set it back to factor settings and restore again from the backup?

If it still does not work, this might be a hardware issue and the phone has to be checked by Apple or an Authorized Apple Service Provider:

Use iTunes to restore your iOS device to factory settings - Apple Support

Find an Apple Authorized Service Provider

iPhone - Contact Support - Apple Support

If the problem has not been solved by resetting to factory settings, the phone needs to be checked by Apple or an Authorized Apple Service Provider.

Did you try to use a different USB cable?

You'll have to get your phone checked, if you choose to visit an Authorized Apple Service Provider or Apple Store next to your place, show them your cable and adapter as well.