reboot and select proper boot device

This message typically appears when your computer is unable to find a bootable device, such as a hard drive or SSD, to start up the operating system. Here are some steps you can try to resolve the issue:

Check your boot order: Restart your computer and access the BIOS or UEFI settings by pressing a specific key (usually F2, F10, or Del) during startup. Look for the "Boot" or "Boot Order" section and make sure your primary boot device (usually your hard drive) is listed first. If not, rearrange the order to prioritize the correct device.
Check for loose connections: Ensure that all cables connecting your hard drive or SSD to the motherboard are securely plugged in. A loose connection can prevent the computer from detecting the drive.
Reset BIOS settings: In the BIOS or UEFI settings, you may find an option to reset the settings to their defaults. Try this option to rule out any conflicting settings causing the boot issue.
Check for drive failure: If none of the above steps work, it's possible that your boot device has failed. Verify this by connecting the drive to another computer or using a bootable USB drive to see if it is detected. If not, you may need to replace the drive.
Repair or reinstall the operating system: If the boot device is detected but still cannot properly boot, you may need to repair or reinstall the operating system. This can be done using the installation media (DVD or USB) for your specific operating system.

If you are unsure about any of these steps, it is recommended to seek assistance from a computer technician or consult your computer's manufacturer for further support.