I am posting this in the linux-software forum since it involves general dualbooting things even though the specific operating system is OpenBSD. I apologize if this is incorrect. Here's the problem:

I used to dualboot OpenBSD and Windows2000, a little while ago, windows stopped booting and I messed around with it and at some point ran, I think, fixmbr. I got windows working but I was very busy for a while and later found, unsurprisingly, that selecting OpenBSD in the Windows NTLDR boot menu resulted in "NTLDR is missing". I booted off an OpenBSD CD-ROM and when running fdisk, I get 3 partitions:
a smaller A6-OpenBSD partition first
then a very large 07-HPFS/QNX/AUX partition (I assume the windows 2000 partition)
then another A6-OpenBSD partition.
I assume the small OpenBSD partition was to get under the 1024 bytes from the start of disk, for booting. The HPFS partition has a star next to it(is bootable) which it clearly is since I can start into windows.

Now when I run disklabel on wd0, it says "/dev/rdw0a is not configured, using MBR partition 0: type A6 off 63 size 2097152, /dev/rwd0c:
16 partitions:
a:
c:
i:"
All with fstype=unused. These a, c, i correspond, I believe, to the partitions listed by fdisk.

There's one other piece of the puzzle. I have an "openbsd.pbr" file which is, if I remember correctly, the first 512 bytes of my openbsd boot partition. This file is in my windows C:/ so that the NTLDR can find the openbsd boot loader.

So the challenge is this: How do I get my openbsd installation booting again, without erasing any data. What did the windows "fixmbr" fix? Did it delete all the partitioning information for the openbsd installation? If so, why does fdisk report that those 2 OpenBSD partions are still intact. Also, is there a way I can retrieve the missing mbr information from this openbsd.pbr file, in any way? The biggest question of all: am I an idiot who has no idea how to use disklabel? Thanks for any help you might give.

You're right about windows fixmbr, it 'FIXES' the master boot record to boot windows, and screw anything else! Ie it removes the partition information from the mbr, but the partitions remain intact.

So you need to figure out if that openbsd.prb file is actually what you think it is and if so figure out where the correct place to put it, but you guessed that much already.

I'm definately no expert on this. If I had the same problem in linux I'd try booting into linux with a rescue disc/distro installation disc and then try running 'lilo' the linux loader which would recreate the master boot record for me.

Alternatively I could goto the /boot dir and using dd copy the backup mbr back in place but this is pretty dangerous if you don't know what you're doing as it raw-writes to the device. (there is also rawwrite.exe for windows)

I'd recommend googling for howto's/faqs/anything to do with dual booting so that before you try anything you're 100% sure it will work - or wait until someone who really knows what they're talking about answers!

There is definately a howto for duel booting linux and bsd, so that could help.

Right, I ended up reinstalling as I was and am still unaware as to exactly what the MBR and pbr contain in terms of file system records. i.e. exactly what did windows fixmbr do to my partition scheme. Its all reinstalled so whatever.