Finding it hard to build a house.

There is a bug report for the error message when trying to place a door. The SimGurus cannot replicate and are asking for saves to try, eventually, hopefully, to fix it:
https://answers.ea.com/t5/Bug-Reports/NEEDS-SAVES-Doors-Windows-sometimes-won-t-place/m-p/9716605/highlight/true#M160369

Edit: For your unplacable/disappearing objects I am clueless. I can't replicate it, but then I don't know the prerequisites. Here is a bug report on some objects not being able to be placed on a plattform, but you did not mention a plattform:
https://answers.ea.com/t5/Bug-Reports/OPEN-Can-t-place-certain-objects-on-platforms/td-p/9723044/page/2

You could upload your build/post a picture/describe more to make it clearer. I hope you have done the usual fixes first though, like updating your game, removing any old mods and cc, clearing any cache, repairing, the game etc.

I quit the broken game without saving and when I went back to that person and put her in the same lot I didn't get the same problems. It's a mystery. I had been playing around with raising and lowering the walls and base layer of the house. But had returned it all to lowest wall height and ground level when I had the problems.