request

[Aneesa Parker]

hello

i am really struggling with grub. someone lent me their laptop for an on-line 
course. i made an awful mistake. 
using grub-config, i changed the setting to 'legacy' instead of 'efi'. 
previously, it was booting properly. ubuntu lts 18.04. no other operating 
system.
now, it just goes into 'grub-repair'. 

i have no idea what to do. i read your book and still don't know what to do.
i am terrified of wrecking this laptop because it isn't mine. he will kill me.
please can u tell me how to fix this.

thank you
yours truly
aneesa