Not Medical Advice: It is a myth that a snake can re-attach its body after being cut in half, as it will die eventually.
However, a dead snake can still bite as its nerves have been recorded to still be active up to 9 hours after a snake was killed. The interval of time had much to do with the snake type, and the situation in which the snake was killed. A snake's head can still inject venom into its victim so be careful of the head when transporting it.
There are some animals that can regenerate limbs and can replace amputated tails, such as salamanders. Larval frogs, or tadpoles, also have this ability; however they typically lose it when they become frogs. Lizards also regenerate their tails, particularly in those species that have developed a mechanism for breaking off the original tail when it is grasped by an enemy. Sometimes, a side tail may be produced if the original tail is broken but not lost.
Learn more about snakes including their diet, behavior, reproduction and more at Defenders.org.
The vast majority of encounters between people and snakes are with non-venomous, harmless snakes. It is critical that you understand that snakes aren't "aggressive" and don't hunt or chase people, but they can strike without coiling first.
Check out some tips on how to safely deal with snakes at Ufl.edu.