Fatal Error – theme functions mess

I am feeling super dumb right now and very frustrated!

I have been searching for some code to allow me to edit the text on a password protected page. I had been able to accomplish this before, but with an update in version it went away. Tonight I found what appeared to be a reputable code, and when I attempted it, I received a fatal error. I was not too panicked, however, as I had copy/pasted the original code into a google doc just in case. When I pasted that code back in, it did not work. I am still receiving the fatal error. I cannot even get to the login page to login – luckily I still have it open on my laptop, but it’s not doing me much good as I don’t know where to begin on fixing. I have done some searching, but I just am not sure.

Does anyone have any suggestions on how this can be fixed, if it can? My website is everydayyou.com/blogsite.