hello im currently using windows 10 Ver. 1909 and here is the theme i am currently trying to get to work now https://virtualcustoms.net/showthrea...-1809-and-1903

and here is an image of the issue I am having


if you go to the link i posted of the theme i'm trying to apply you can obviously see something is wrong.
I'm pretty new to this kind of thing and have only done it a few times, and I'm pretty stuck. If someone could give a quick explanation of how to just go back completely to default without having to reinstall windows so that i can try it again that would be great, or obviously if you've seen this and know how to fix it that would be ideal. Thanks in advance to anyone who spends time trying to help me out!