BOOTMGR Missing/Temperamental repair help?

[Rival Son]

Recently My PC keeps booting to back screen with just mouse.. other times I am getting the "BOOTMGR is missing" error.
After a couple of reboots it booted in to windows.. So now.. Is there a way to repair bootmgr issue WITHOUT a disc drive? I don't have one just now, but I have ordered one..

Obviously I am backing up critical stuff just now in case, just wanted to know if it's possible to sort?

Thanks
Rival

 

[smorizio]

use hdtune check for drive failure and hardware vendor tests. download and make from usb stick a hirem boot tool cd or usb stick that has tools to fix mbr issue. also from the pc if it working with a usb stick and widows media creation tool that free you can make a new bootable usb stick with the os on it. boot from it go into dos mode on windows installer and run diskpart commands a list of them are online.