emergency brake will not release

My husband set the emergency brake on our jimmy the other day and now it will not release. At first we thought the line may have frozen, but we have had a couple of nice days lately and it still will not release. Anyone have any ideas as to what we should check? I need this fixed so my husband can get back to work.

What year vehicle? 2 wd or 4wd? disc rear brakes or drum rear brakes?

Make sure the emergency brake is fully released on the inside of the vehical.
Lay down on the ground next to the front of the rear tire and looking behind the tire you will see a stiff cable runnung to the backing plate.
Grab that cable and wiggel it arround like a worm.
use two hands, twist wiggel push pull and basically move the caseing alot.
This should get you back on the road but technically the drum should be removed and the cables pulled on from the inside of the drum.
The method above will work and it needs to be done on both sides.
You may even need two people doing this at the same time.
you need to put alot of moveing pressure on the cables so twist away.
Kind of like your trying to break a stick type of movement.
Of course you dont want to bend it right in half, just enough to free the inside cable from the casing.
RUEL OF THUMB.....
If you dont use your e-brakes every day,... dont use them at all.

edit:
It is best to do this with the rear on jack stands so you can turn both tires freely.
also, you will know they are free.
when the term frozen is used, it means the cable is rusted to the inside of the liner from not being used.

it is a 2000 4wd, drum brakes.

Thanks G.A.S., we will try it.

Also using something like WD40, or something a little more stronger type penetrant, spray it on the e-brake line from where the cable goes into the shield, and let it penetrate into the line. Use GAS's method to free it too and pretty much either keep working the brake, by using it, or don't use it at all or it will stick.