Will Making my Disk EFI Bootable possibly Destroy the Disk?

Ok, So I’ve been having an issue ever since I tried Partitioning my Windows side so I could get more space. But I messed it all up and now I keep getting the error, No bootable device - insert boot disk and press any key.
I’ve been watching some tutorials online (since I’m not too experienced with Computers) and it seems that your software will help me by enabling the disk to boot on ETI, But the Narrator says “I’ve already done it and it could mess up my system”. I’m scared i’m going to lose everything from my Windows side and I don’t want to mess up again.
I just want to know if it will destroy my disk if I don’t know what I’m doing, and if you could apply me with some help on this, it would be greatly appreciated.

it cannot destroy anything
it writes EFI/Microsoft/Boot to EFI partition