18.04 – location of new kernel for grub rescue?

by changing the color of the startup screen, I could not restart in GDM.

In the Grub command line, I tried to mount the SDA file to fix it, but the message says that the mount point does not exist.

I've also tried auto start repair under FOSS. he says the repair was successful, but he could not start in GDM either.

so I tried the instructions here:

https://www.linux.com/learn/how-rescue-non-booting-grub-2-linux%20%20

but i have a problem when come to this step:

grub> linux /boot/vmlinuz-3.13.0-29-generic root = / dev / sda1
grub> initrd /boot/initrd.img-3.13.0-29-generic

The original kernel installed is 4.15 generic which I deleted after upgrading to 4.19. but in the / boot directory of the root device, I can only find vmlinuz and initrd.img for version 4.15.

Is there another location where the newly installed 4.19 kernel is kept? I improved it using UKUU