Can't replace lots and can't build

TheEnlows​  Please test a(nother) new save in a clean user folder.  Move the entire Sims 4 folder out of Documents > Electronic Arts and onto your desktop.  When you launch the game, a clean folder will spawn with no content.  (Your saves and other content will be intact in the folder you've moved but temporarily unread by the game.)  Don't add anything to the new folder yet; just start a new save and test build mode on at least a couple different lots.

If build mode works fine, you can copy your main save to the new Sims 4 folder, but nothing else yet, and test it too.  Since you're copying rather than moving the save, you don't need to worry about the effects of any missing mods or custom content.

If build mode is still broken for you, please provide a dxdiag.  Click Windows key-R, enter dxdiag in the run box, wait for the scan to finish, click "Save all information," and save the file to your desktop.  From there, you can attach it to a reply using the paper clip (Attachment) icon included with the other formatting buttons.