It seems like your HDD has been affected when it fell. Please do try these troubleshooting steps that may help.
- Start by loading in BIOS and see if your HDD is still listed.
- If it's listed make sure to set it as the first boot device.
- If it doesn't boot up and give your the same error "Reboot and Select Proper boot device" try reinstalling Windows again.
If this will not work then it's the HDD that is faulty.
- You can try taking out the HDD and put it onto a different PC and see if it would work or not.
- You can also try loading the OS using a different PC just to see if it would load or not.

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