I've collected snakes from the wild which were missing their tongues. W/c snakes missing tongues were pretty emaciated, but in captivity, were able to feed when offered killed prey or when the prey was trapped in the cage with no where to run, in those cases where the prey was an amphibian, fish or worm. Rodent prey was always offered as dead food.
I have a Sonoran whipsnake which appears not to have a tongue. She feeds OK on fuzzies, although her intervals between feeding are longer than what I'd expect from a racer. Perhaps she needs to be extra hungry to just open her mouth to a food item if she has no tongue to help stimulate feeding. I think snakes do have at least some sense of smell, and probable some sensation in their lips. The tongueless racer eats while hiding under her bark, so I still don't know exactly how she initiates feeding but she does it.
There may be hope for a snake which has damaged or lost its tongue. Snakes are capable of learning, and might figure out how to feed even if impaired. Such a captive may be a special-needs animal for the rest of its life, and if you plan to keep it, you could face a bit of extra work with it. My tongueless whipsnake is no problem, as she accepts food placed under her bark, but I doubt she'll be as robust a captive as a snake with its tongue intact.
