Stuck on GRUB command prompt after regular kernel update
You don't need a live CD to solve this.
Type:
grub> ls
Here you should see a list of devices/partitions. Now we must find the partition that contains "/boot"
grub> ls (hd0,gpt1)/
The slash at the end is necessary. You may see "msdos" instead of "gpt". If this is the right partition we should see:
boot etc root bin ...
Type:
grub> set root=(hd0,gpt1)
grub> linux /boot/vmlinuz...(Press tab and choose the last working version) root=/dev/sda1
grub> initrd /boot/init...(press tab and select the same version as above)
grub> boot
This is just an example, you should modify it accordingly.