Catalina OS crash - what do I do?

mashant wrote:

Hello. I'm on a MacBook Pro (2014) where I made a Bootcamp partition for Windows after installing Catalina about a month ago. Today while on the Mac OS the computer abruptly shut down. When I turned it on again it went straight to Windows and I cannot get it to reboot in Mac OS.

In Windows if I go to Bootcamp settings (Start up your Mac in Windows or macOS with Boot Camp - Apple Support) there is only the Windows option displayed, no Mac OS, suggesting something has gone wrong with the OS. I can still use the computer but in Windows only. How do I fix the Mac partition which I normally use 90 percent of the time and which has files i need?

Hold the Option key on start up and see if you can select the Macintosh HD from the start up manager.

How to select a different startup disk - Apple Support

If this is not possible—

Boot into Internet Recovery (Option Command R) and from the dropdown menu: Utilities>  Disk Utility> run the First Aid on your Macintosh HD (and the "Macintosh HD-Data" volume as well if Catalina/Big Sur) If errors are found and repaired, run again until no errors reported.

Disk Utility>View>Show All Devices The best sequence is —

• Volume level

• Container level

• Parent drive

Recovery: https://support.apple.com/en-us/HT204904

If no resolve You can also restore form backup—

—How to use Time Machine to back up or restore your Mac: https://support.apple.com/en-us/HT201250