Turned off everything in folder /LaunchDeamons with launchctl; can’t boot now—how to recover?
You should be able to fix this in single-user mode. Restart the Mac while holding the Command and S keys; it'll start into a full-screen command-line environment, with none of the usual daemons even trying to run. As usual, the first two things to do in single-user more are to check/repair and mount the startup volume. To check/repair it, run the command /sbin/fsck -fy and wait for it to finish. If it prints " The volume was modified ", run it again and keep running it until it finishes with "** The volume  appears to be OK." Once the startup volume is OK, mount it with /sbin/mount -uw /

Once that's done, run the command:

rm /var/db/launchd.db/com.apple.launchd/overrides.plist


(Note: type this command very carefully. If you thought the damage from mistyping that launchctl command was bad, you haven't seen what a garbled version of this command could do!)

Finally, run the command reboot and the system should restart normally, with all of the system LaunchDaemons set back to their default states.