Sounds like it may be slow charging, as if it was plugged into a USB port instead of a wall charger.

If it is plugged into a USB port of a computer or a laptop, this is normal.
But if it is plugged into a wall charger, then there is a problem.

Plug in the charger, start at your homescreen, then go to:

Settings
scroll to Battery
Usually, right by the Battery selection in the Settings (before you actually select 'Battery') you will see where it gives the percentage and it should say Charging on AC or Charging on USB.

If you are using a charger plugged into the wall, then the phone should say Charging on AC. This is the fast charge.
If it is plugged into a USB port, then the phone should say Charging on USB. this is the slow charge.

Sometimes, you can be plugged into wall charger, and the phone will still say Charging on USB. This will cause the symptoms that you describe.

If you can replace the cord between the phone and charger, that might solve the issue.
Sometimes the charger itself can go bad.
In my experience, it is usually the cord.

There are a couple apps tht I have used to trouble shoot what cords work well, and which ones don't.

CPU Float is a great app with no ads.
It is for more advanced users.

Ampere is another app that will work, but it does have in app ads.
It is easy to use.

What you want to do is run the app, and then get a milliamp reading for each cord that you try.

Use the cord that gives the highest level of current to charge your phone.

Cords with low current capacity might not work good for your phone, but you can still use them for other things, like bluetooth speakers, auxillary batteries, etc.

Hopefully, this will solve your problem.

 

If changig cords did not solve the issue, then it is time to look at the charger itself.
If you have another charger, use the cord with the highest milliamp capacity from your earlier tests, and try it with the different charger.

If you are still experiencing the problem, then you need a flashlight, and maybe a magnifying glass as well.
You should inspect the jack on the phone itself.
The contacts are very small, and any dust or debris that gets in there can cause a poor connection.

You could try some compressed air (the same as what is used on computers) to blow out the jack.
A toothpick can be used VERY CAREFULLY AND GENTLY to remove anything that cannot be removed otherwise.

Remember that these contacts are very small, fragile, and easy to damage!