[SOLVED] Unable to start PC: Bootmgr Missing

[heartkiIIer]

Hi all, so my PC is currently a Windows 10 which I updated from Windows 7 a while back, and this is a pretty old PC so when I tried to follow other online solutions of entering the BIOS, it just doesn't work since I have what's called the CMOS Setup Utility instead and I was not able to find solutions for that interface. So when I first start the PC, it shows me this screen.

https://imgur.com/a/UgI0h4m

Then it goes to this screen:

https://imgur.com/a/WgCh3sG

Now when I press Ctrl+Alt+ Del, it goes back to the above image and this time I press DEL, and I'm presented with this screen:

https://imgur.com/a/z3mGeiw

When I choose "Advanced BIOS Features", I get this screen:

https://imgur.com/a/6x3hdCx

When I choose "Standard CMOS Features", I get this screen:

https://imgur.com/a/FFghlnu

When I choose "BIOS Security Features", I get this screen:

https://imgur.com/a/xyZRo4b

Now when I go back and start my PC again, and this time I choose F12, I get this screen:

https://imgur.com/a/w1cGAmg

I am in need of desperate help to get my PC up and running again. My PC doesn't have a CD/DVD slot so I can't load a Windows Repair DVD either. Any help is appreciated!

 

[SkyNetRising]

Is this the same pc, you were trying to convert from MBR to GPT ?
It doesn't support UEFI boot and can not boot from GPT drive.

 

[heartkiIIer]

Is this the same pc, you were trying to convert from MBR to GPT ?
It doesn't support UEFI boot and can not boot from GPT drive.

Yes, it's the same PC. But I hadn't converted the drive to GPT yet. It's still MBR.

 

[heartkiIIer]

I was able to reboot my PC using a bootable drive.