My phone won't charge

@meganmarie you are not giving us enough information. It will help if you let us know if anything happened to your phone. Did it just stop charging? What have you checked and what have you tried to fix it?

First, you want to check your charger and charging cable. Make sure it has the proper voltages. Check to make sure that the cable connectors are not bend etc. After that, check the charging port. Make sure there is no corrosion, debris etc. that prevents it from working. Clean it of any debris etc, use a few puffs of air to clean it out. If none of this works, get an ammeter and see if your phone draws any amperage from the charger.

You may also have to consider replacing the battery. A depleted battery can no longer be charged. Measure the voltage on your battery connector with the charger plugged in. You should get around 4.2V If you don't get that voltage check your flex cable coming from the charging board. Make sure it is seated properly and does not have any tears or other damage on it. (common withthe A series) Your phone has a separate charging board that could be faulty, consider replacing that.

Since iFixit does not yet have the guides for these repairs, use a video like this one for the charging board. The charging board as well as the battery is available at many online stores. Just ensure that you get one for your exact model SM-A102(U, U1, W, or DL).

While you work on your phone, take lots of pictures. Once you are done with it, take those pictures and create a guide for iFixit. That will help the next person that has the same problem as you do. It's easy and fun to create these guides. https://ifixit.com/Guide/new The iFixit community will appreciate this.