I started to get into smoking pipes 5 or 6 years ago, and really enjoyed it, but, then I put myself into a financial crisis, so I had to put all my good hobbies(pipes, cigars, buying guns) to a stop on hold.
I just found a cigar box full of ziplocked pipe tobacco in a closet, that has been sitting untouched for about 5 years. I instantly remembered what each one tasted like, and almost got giddy with excitement.

Now, to the question. How do I revive them? They are not as dry as paper, being only slightly more moist then cigarette tobacco.

Please help!

ETA: I put in an order at pipesandcigars.com last night after reading What's in your bowl? last night, so fresh tobacco should be here some time next week.

Slices of apple will help to restore moisture to tobacco.

Try a bowl at the current moisture level and see how it is. Most pipe tobacco could use some drying IMHO.

To a certain extent, yes.  However, if it's bone-dry it's a loss.  All tobacco contains oils.  Once the moisture is completely gone, the oils are pretty much toast and won't come back.   Most all pipe tobacco, especially aromatics (which IMO are anyway)  is too moist.  Whenever smoking tinned tobacco (especially flakes) I usually let a bowlful sit out a couple hours before smoking.  

As a general rule, I try to keep produce out of my tobacco and vice versa.

OP if you buy your tobacco in bulk, go to the grocery store and buy a case or two of Ball or Mason canning jars.  Wash them in the dishwasher first to make sure there are no mold spores etc.  Once dry, fill with excess tobacco and let it go.  It will continue to age well and it will maintain it's humidity.  I have about 50 jars of 8 year old Penzance, FVF, Best Brown, Stonehaven, etc.  They've been aging wonderfully and most have wonderful crystals formed on them

You can rehydrate by putting the tobacco in a bowl, like cereal bowl size, then cover with a moist (not dripping) paper towel, repeat as needed until tobacco is at proper humidity. As mentioned though, it may never be as good as it should be due to the loss of oils but you can give it a shot and see.

What brands/mixtures are we talking?
Me personally, if I could afford to/find the same blends again, id just buy more and mix it up letting everything settle out. Most pipe tobacco is too wet as it is.

Or in the case of OTC's no rehydrating necessary! Ive smoked SWR older than I am and it was just about right. Yes, it was open and in its original can.