screen ghost my phone

Generally the so-called "ghost touch" problem is caused by an issue with the digitizer or touch screen on the phone. Since it's fused with the display, you have to replace them both as a single assembly in order to fix the problem. I wasn't able to located a guide for the A03 Core version, but here's one for the standard A03. Hopefully it will be close enough that combined with a little common sense you should be able to do the repair.

Manuals / Samsung Galaxy A03 / Full screen

I usually start with sites like Amazon, eBay and AliExpress when looking for parts, depending on how fast I want it vs. how much I am willing to pay.