This is often the sign of either a sick, depressed, or especially a chilled
[7.3] hedgehog.  Assuming your hedgehog is warm enough, and there is no
likelihood of unusual stress (which can also put a hedgehog off eating), you
may want to have a vet check for sickness, but clearly the thing that's
needed is to get your pet back on its dinner.  About the only suggestion I
can offer is to attempt out-and-out bribery; offer your hedgehog his favorite
treats, and try some cooked chicken or turkey.  If possible, make sure he is
drinking, and if necessary resort to using some thinned chicken broth, or
even something with electolytes (see below).  Other suggestions for bribery
snacks are chopped hardboiled egg, cottage cheese, and mealworms.

Here are a few words of wisdom from Linda Wheatly on getting a hedgehog
to eat:

    If the animal is warm, but not eating, first try varying its diet.
    I will often try raw meat [please note that there are dangers to using
    raw meat as outlined in section [6.2] -- ed.], which often works.  I 
    recently discovered an appetite ``picker upper'' which hasn't failed yet.
    I raise mice also, and will give the poor-eating hedgehogs dead pinky 
    mice.  Hedgehogs will also eat the bigger mice.  If all else fails, and 
    the animal refuses to eat anything, they can be force-fed.  I beat an 
    egg [there can also be dangers with using raw egg, as outlined in section
    [6.2] -- ed.], add a little bit of milk and a tablespoon of corn syrup.
    I take a 1 cc syringe and gently work it into the side of the hedgehog's 
    mouth and slowly feed the mixture in.  I generally feed 3 cc's four times
    per day.  If the animal is looking dehydrated, I may give it 1 or 2 cc's
    of water with each feeding.  You may have to do this for 4 or 5 days.
    They will start eating again on their own.  They will often show you
    that they are wanting to eat by themselves by really fighting you 
    when you try to force feed them.

Related to this is the problem of not drinking, or not drinking enough,
resulting in dehydration.  If water is available and accessible, this is
usually not a problem, but if for one reason or another this does occur, it
is important to get fluids into the hedgehog as quickly as reasonably
possible.  This might involve a vet visit and intravenous or similar fluid
replacement.  In less dire cases, you can use electrolyte enhanced drinks,
such as many of the sport drinks now available, or better yet, Pedalyte, a
form intended for children, which is quite a bit `safer' for sensitive
digestive systems.  Because of the cost, and quantity, this is not always an
economical choice, however, as suggested by Sheri, you can get it in a
powdered form under the brand name Kaopectalyte.

Remember, given a hedgehog's small size, not eating or drinking can become
deadly in very short order.  If the situation persists for more than a couple
of days, consider taking your little friend to a vet.