Mechanical Issues 2000 Plymouth Neon

Does anyone know how to fix the gas gauge on a 2000 Plymouth Neon. Recently, we just filled the tank with gas. Now I know for sure that the tank is completely full as it cost me $35 tot fill it. This, issue is with the gas gauge. Even though the tank is full, it's showing Empty. Is there anyway to fix this without it costing a fortune? I have no mechanical experience, so any help would be appreciated. Thanks in advance for your help!!!