The question mark shows up when the last-used disk containing a valid MacOS can not be found, or that disk no longer contains a bootable version of MacOS. This can be caused by disk corruption.
From Recovery, launch Disk Utility and Repair/FirstAid the disk, run it repeatedly until it comes clean or is hopelessly stuck.
if stuck, how to proceed depends on whether you have a Trusted backup copy of your files.
if you do [have a Trusted backup copy of your files] the drive can be Erased, and a fresh copy of MacOS can be installed, and you can restore your files from backup.
if you do not [have a Trusted backup copy of your files] you need to use Startup Security Utility to allow booting from an external drive, then connect an external drive, and create a fresh copy of MacOS on the external drive. Then boot from the external drive and you can attempt to rescue some files from the damaged Internal drive.