When we bought our farmhouse, it had not been occupied for thirty years, and had been without windows for the last ten of those. Yes, we bought the local abandoned 'haunted house'. My husband remembers dirtbiking here with his siblings when he was a kid, and sneaking through the rooms. It was already a broken-down old place then.
Of all the doors in our farmhouse, the only one still hanging was the front door. All of the other doors had been ripped off their hinges and thrown out the (already broken) windows. Any slightest bit of hardware, be it decorative or utilitarian, was stripped. The mantels were gone, as were sliding wooden pocket doors and even the stair railing and baluster (which is sad,as those old railings really give character to a place-and of course, they were all hand-hewn back then).
We managed to salvage and re-use all of the doors- but we had to scout around for the right hardware and knobs.
We did our best to improvise with our findings, and I think we did pretty well. All of the doors had keyholes in them. I guess those were the days when everything was kept under lock and key- we even found a rusted old key when digging out the flower beds.