corns snake not eaten for 4 months ?

Question
please help me by helping my son, he has had his corn snake for 13 months now and he has had no problems feeding him until the last 4 months he hasn't eaten it's mouse. please what can be the problem as we have tried everything every vet and shop has told us. My son has been told to force feed him but we are not prepared to do that. Plese is there any thing u can suggest we can do,

Answer
Let me start by saying this doesn't sound good.  Has the snake actually been seen by a vet?  Was a "fecal float" test done?  What were the results?  Did the vet check for cryptosporodosis (sic)?   Not eating is a symptom NOT the problem.  My guess is your snake has internal parasites, those must be treated before anytihng will work.  Force-feeding won't help as his digestive tract is probably useless at this point.  Let me know some more details.