Deleted parts of the Code on Wordpress Editor page. Website looks terrible!

I had finished my website and there was a few lines of code at the top of it that could be seen by clients. I went into the Editor page to see if I could erase the code on the Editor page, that looked similar to the code at the top of my sites home page. I feel like an idiot bc now the website is pretty ruined and I can’t figure out how to just restore what was there (didn’t do any back ups) or just scrap that all together and start fresh. I am not able to install anything new (not even free themes) without them looking odd. Anyone have any help for (obviously) a total novice?