i used the shrink modifier to make the clothes. i hide the clothes and did some changes to the body. but, even though i unhide the clothes in the outliner the clothes dont appear. why does this happen.
Looks to me like the clothes are there. they have a different color right? It's just that the clothes are shrinking to the surface of the character.
If I'm right... if you add a solidify modifier and play with the offset on it, you should see the thickness of the clothes.

Ok... but here, the black looks like clothes.. so it's not that your clothes are disappearing, but that they're being shrink wrapped onto the changes of your model... so that might be why we're not understanding the question and what you are trying to do... try giving us more info.
and like I said before, it might help if you showed us a screenshot of your modifiers if you're still having problems with this. Might help if you show us the full screen shot instead of a zoomed in piece of it.