Display not lighting up. My son squeezed my phone real hard and now the display won't light up.

Question

My son squeezed my phone real hard and now the display won't light up. Several weeks later, the ringer started ringing at a lower volume. This volume lowering continued until now I cannot hear a ring at all. Can you tell me how to fix this? And what parts should I get? It would probably be cheaper to just get a new phone, but this one was my first cell phone given to me by my granddaughter and I would love to repair it and just save it for sentimental reasons.