So you can't even climb down? I didn't even know anything was that steep (I essentially don't climb at all).
I believe it is possible to hack the save to move your character, but I don't know how to do that myself. With a bit of luck somebody with that knowledge will post a description of how to do it.
Unless your homestead is on a water tile you're zoomed in to the wrong tile, as you've ended up on the water tile rather than terrain that is normally available for zooming in. There is a long standing bug in auto zoom in causing my characters to zoom in to a tile one step away from the one they zoomed out from, so I've disabled auto zoom in to homestead (manual zooming in works correctly).