Kristjian Kimono

Sorry to be a pain but how do I reset the sim?

I was building a house on my land and decided I didn't like it and wanted to start over, so I selected all my objects and deleted them, they dissappeared and my land info says that there is not a single prim on my land, but when I try to fly or build its like the roof and ONE wall is still tehre, everything else is like it should be but I have an ivisible roof and a single invisible wall that I cant fly through and makes the floor of the new build useless cause I walk up into the air as if the roof of the old build is still there. I thought maybe it was just a too-recent delete so I erased everything of the new build and waited a day, but the phantom roof and wall is still there. Help?