Open Core Legacy updated

Hey guys!

Sorry for this question, but i’m scared i fucked up.
So i have a MacBook from mid 2014 and someone installed Open Core Legacy on it to run a newer version of the os.
Today i had the great idea to update it ( the most stupid idea i ever had ) i have stored all my Icloud photos on this MacBook ( on the drive ) and now my screen is super small and i can’t even login to my account… i feel so bad and stupid to be honest, this is the first time i ever saw or heard about this OCL.
I tried googling to see if there is a way to revert or to get into the ocl menu, but i can’t seem to get it working, my question was: is there a way to fix it or revert it? Are my photos gone and did i fuck up?

Thanks in advance for helping a noob in ocl, i appreciate it a lot!