When I learned wu'du it included the whole body, including the private parts. It was noted to me at some point that this part of the ablution must be repeated after using the restroom. However, somehow I think I heard another source say the whole of wu'du must be repeated at that time. What is the answer?
It sounds like you are confusing ghusl and wudu.
Ghusl is a full body wash. It is required in order to lift a state of major ritual impurity (intercourse, ejaculation, menses, post-partum bleeding).
Wudu is simply ritual ablution, required to lift a state of minor ritual impurity (such as from using the restroom or passing gas). It only involves rinsing the mouth and nose, washing the face and arms and hands, wiping the head and ears, and washing the feet.
Wudhu becomes void when at least one of the following seven things happens:
1.Passing of urine.
3.Passing wind from the rear.
4.A sleep that is deep enough to restrict sight AND hearing. so if the eyes do not see anything, but the ears can hear, Wudhu does not become void.
5.Things because of which a person loses his sensibility, like insanity, intoxication or unconsciousness.
A person enters the state of Janabat in two ways:
2.Discharge of semen, while sleeping or when awake, No matter whether it is little or not, with lust or otherwise, voluntarily or involuntarily.
Ghusl for Janabat is obligatory for offering the daily prayers. (You should first make a niyyat(intention) for Ghusl. Then you should first wash your head and neck, and thereafter you wash the right part of the body first and then the left part.)