Probably, you mean BOOTMGR rather than BOOTMSG.
That's not good news. It's fixable:
Windows error message "Bootmgr is missing Press Ctrl+Alt+Del to restart"[
^]
But...if the boot sector is missing or damaged, you need to find out why. If it's software, then it's probably malicious and you need to find and eliminate it. If it isn't ... then you probably need to think about getting a good solid backup and replacing your HDD. Disk errors don't "go away", and they do get worse - normally very quickly.