Don't give up..
As others have said, there are plenty of resources available, just have
to look around.
Having restored an old WWII era Zenith myself,
Here's what I would do...
Note the Make, model number, even serial number.
1. Don't power it up yet, dried up electolytics capacitors tend not to
take too kindly after sitting for so long.
2. Go to your local library, a main downtown branch is the best
resource.
They can help you locate the schematic diagram for it (somewhere in the
technology section). You may even find one pasted inside the chassis of
yours.
3. With Schematic in hand now, find someone local who has access to an
old tube tester.
Call around to various TV Repair shops, someone has to have one laying
around somewhere. Use this resource to test the condition of each and
every tube in your radio.
They can give you a recommendation on which ones might be toast, a
little weak or in good shape.
4. Based on 3, Look for any tubes you may need, search around the net,
ebay included, and wait around till a local hamfest arrives in your
town (springtime around my area). By this time you'll have a good idea
what you need to look for and ya might just get lucky right there at
the local hamfest.
5. While your waiting to find any spare tubes you may need, try to
locate the electrolytic capacitors in your chassis. They stand out as
rather tall auminum can lookin things. These are what tend to dry up
over the years and can cause grief, and have been known to just "POP"
upon applying power for a while after sitting so long. It's probably
best to just wholesale replace every one of these assuming you can find
suitable replacements, which normally isn't too hard (again hamfest).
If they aren't toast today, they will be shortly anyway.
6. Now you may try to power the thing up again and see what happens. If
it works well, fine. If not, there are other capacitors that some
restoration folk will just replace as well. These would be any
interstage coupling caps, bypass caps, etc. At this point is where the
schematic helps a lot.
7. Some restoration folk may even recommend re-wiring the whole thing
as well
depending on the vintage. In my case I went ahead and did that myself
as well, being from
WWII era it used really crummy wiring and insulation (copper was
conserved for other obvious uses back then).
Mine has this really cool speaker and sounds awesome, it uses an
electromagnetic speaker. Modern speakers use a a permanent magnet for
the voice coil to drive thru.
It's a 1941 Zenith tabletop with mechanical pushbuttons for AM
broadcast station presets. And does two bands of shortwave as well. Put
a lot of time in restoring it, but it was a lot of fun.
Good luck
p.s. - I found it at a yard sale for 20 bux, offered 'em 10 and it was
mine