Also you casn try getting it to start eating by cup feeding with a live rat pink or something else that is unable to hurt the snake. Make sure the delicup is opaque and has air holes, or use a breathable brown paper bag. Leave overnight. No guarantees but works great if the reason is fear.
Also don't stay there and watch it. I have snakes that won't eat anything until I gave up and left the f/t rodent there, as soon as I left the room, it ate. Came back an hour later rat was gone. This was after months of trying to get it to eat.