What can I do about my mother who won't eat?

The first step might be to get to the bottom of why she won't eat. There are so many things that can cause elderly stop eating. Some medications can cause loss of appetite or loss of taste. Is she depressed? Dental or gum problems might be a factor. If you feel comfortable, talk to mom about why she isn't eating. If she is unwilling or unable to discuss the problem, then bring it up with doctor to see if he/she can find the reason for the loss of appetite - and hopefully the doctor will be able to help you come up with a solution.