Zorin Dual Boot on a MacBook Pro Problems

I successfully installed Zorin 16.3 on my old MacBook Pro (2012). For a while, it seemed I could toggle between Zorin and the Mac just fine. However, recently I tried to access the Mac OS and found that it lost OS image and wouldn't boot up. I tried to restore with Disk Utility. Unfortunately, I didn't keep a Time Machine backup of the system. So I tried to restore from the web, but that didn't work either because it said certain components couldn't be found. Then I tried to erase with Disk Utility, and found that I now can't into Zorin as well. I'll probably have to reinstall Zorin from a USB. I don't know if I can ever restore the Mac OS paritition. I don't really need the Mac OS, but certain things like iMovie and other graphic software were nice. Any suggestions?

Partition the drive how you want, install MacOS and then Zorin.

In the future, keep a timeshift backup if nothing else.

Thanks. That's how I did it the first time. I had MacOS on there already. Then I partitioned the hard drive and put Zorin OS on the second partition. I took a timeshift backup. However, I did something to damage the Zorin installation, I couldn't get to the backup. I guess my first problem is to see if I can get the Mac OS reinstalled. If I can't then I'll make the whole laptop Zorin.