No not the grub.d folder or the grub.cfg file. Btw if you changed the grub.cfg file, do change it back. The line should not be there.
But it is;
the grub file in the folder /etc - there you wil find the file and try to find the line GRUB_CMDLINE_LINUX_DEFAULT=
You can add " nomodeset" to the line. If that is the solution for your problem.
