How can i get my grandmother to start eating again?

Maybe you can't: But it's worth a try. Few suggestions - make foods you know she likes. May consider spicing a bit more heavily - but not too much on the salt. Try different textures. Try multiple small meals throughout the day. Use ice cream based drinks. Ensure there is no jaw pain, weakness, constipation, abdominal pain, urinary tract infection or swallowing difficulty. Sometimes this happens at end of life.