I'm running XP . I completed all three houses but I spend most of my time at the house west of Riverwood . I had traveled back to Windstad three or four times after it was finished then recently noticed the map marker had disappeared so I went to check it out but when I arrived everything had reverted back to bare land . This included the drafting table, chest, anvil etc. Then I went to Morthal and I found the house carl sitting in Highmoon hall . I was hoping the Jarl might still have the speech options to buy it again but no luck there . I have been playing Skyrim since it first come out and have seen a few strange things but this is a new first for me . Apparently a completely new glitch .
Thanks,
Hagar