Boot Mgr Missing after protable Linux Crashed

[RakibKhan]

A few months ago I created a portable Linux(ubuntu 14.4 lts). uses it many times. but yesterday I faced a strange problem. suddenly my portable Linux crashed and after then an error message showing Operating system not found press Ctrl+alt+del to restart somehow I manage to fix this issue(from the internet, they said it is happening because MBR gets corrupted. I have no idea ) now, after fixing this MBR issue, I'm facing another problem, that is now another error message showing Boot MGR is missing 1.i don't have any system repair disk. 2.i have 2 os(win7 and 10) on the same hard drive. 3.automatick repair not able to fix my problems.and none of the cmd commands working.   is there any solution without formatting my hard drive? can't I just copy a boot record from another computer and paster into my computer?