photo #6815843

So I have a piece of property that I've owned for 30 years in a small town they have suddenly changed all of the lines to where the city thinks they own half of my property I need help to know what to do because I paid for this property 100% And I own 10 ft past my building now they say I own 10 ft into my building to them. Please help me if you can tell me what to do. They're after us