You can doing these steps which will give you a new fresh assignment and reimplement the code, please doing these steps file → open → select running assignment and doing shutdown and select all file and delete it → after that select help
You do have to get the existing file out of the way in order to have “get latest version” give you the new clean copy. But if you “rename” it, instead of deleting it, then you could “copy/paste” any legitimately completed work from the old notebook to the new one. But as we see in this whole topic, “copy/paste” needs to be used with care! But just wanted to make the point that you don’t have to start completely from scratch. Your choice!
Just for reference, here’s a thread from DLS that explains in detail how to go through this whole procedure.