> 
> Is there any way to restore the data from that drive?

Yes - but the cost may depend on how/why it is broken!

It might be enough to specify the first alternate superblock to fsck.
(try fsck_ffs -b 32 ...)
If that fails you might be able to locate one of the other (many)
alternate superblocks.  Beware though that fsck can completely trash
a filesystem if it starts playing with an incorrect superblock [1].

Also, are you expecting the filesystem to start right at the beginning
of the disk?
That label might be a 'ficticious' one generated by the kernel.

Which version of netbsd are you using?
What does 'hexdump -C -n 24576 /dev/wd0a' give?

	David

[1] I managed that while playing with disklabels....

-- 
David Laight: david@l8s.co.uk