I seemed to messed up the artwork or something when i deleted some default stuff in rom folders to make the systems go away from ui. How do i fix this without reinstalling everything again.
pic of problem
To completely replace the broken theme (in RetroPie 2.3 or 2.4, at least), delete the /etc/emulationstation/themes/simple folder and replace it with the simple folder from the downloaded zip file. I would make a backup first, just in case.
Once it’s working, if you want to try editing it again, I would recommend making a copy of the simple folder with a different name, and making the edits there. That will effectively create a new theme that you can switch to from the start->UI menu in EmulationStation. If that breaks, you can always switch it back.