Sierra stuck at boot screen, upgrading to mojove will create new bootup files? I am facing some issues in High Sierra . Since few days it's stuck at boot screen and load very slow, mac doesn't start even after completing the load progress bar. But when I charge it fully and after some time it start accidentally, and then after some time when i try to open it's not booting up. 

Other problems are Command + R is not working on this OS and i am not able to recover when it's not booting up, even I tried netboot but globe was spinning and after completing the progress bar, it doesn't show any option instead apple logo appears again and then stuck at boot screen.

I am now going to upgrade High Sierra  to Mojave, I want to know if I am installing or upgrading to Mojave will it correct the bootup files and solve this issue and Command + R will work?

My os details :

MacOS High Sierra
Version : 10.13.4
MacBook Air (13-inch, 2017)
Processor 1.8 GHz intel Core i5
Memory 8 GB
I also suggest better to upgrade and mostly it might fix your issue. Kindly use the following keyboard combination as per your requirements. 

Basically, as per Apple Guidance:

Command (⌘)-R Install the latest macOS that was installed on your Mac.

Option-⌘-R Upgrade to the latest macOS that is compatible with your Mac.

Shift-Option-⌘-R Install the macOS that came with your Mac, or the closest version still available.