The tank may be too cold. This will make the mouse to rot in your snake, finally causing the snake to regurgitate.  Additionally, the mouse may have been to large.

Make sure your tank is warm enough and the mouse is not too big.  Your snake might also be in a mating cycle or a brumation cycle (a semi-hibernation state).  If a female is full of eggs she will stop eating.  If the day length has shortened, your snake might slow down eating.  Finally, if your snake does not feel secure, he might stop eating.  Provide him with one or two nice hiding places.  To entice a snake to eat, try both dead prey, then live prey.  Try feeding your snake during the day, and then at night.  A towel over the tank may help, as will snipping open the dead mouse’s nose or head.  If you do not resolve this problem, take your snake to the vet to rule out bacteria, protozoa or worms.  When your snake defecates, collect the feces in a clean bag and take it to a reptile veterinarian.

Unfortunately, inbreeding to create “cool colors” has resulted in some quick and unexplained deaths in corn snakes.

This is not a problem.  Your healthy snake is due to shed!  If you watch, your snake’s eyes will clear, and he will begin to shed.  Soak your snake in warmish water after his eyes clear to assure proper hydration.  This will enable your snake to shed within the next 24 hours.