solution depends on your version and you should change some numbers
suggested fix :
you should know which partition root directory is located in , so do ls and see what partitoons you have then do ls(hd0,$number) until you find your root
after this you should find your vmlinuz and initrd version , if luckily yours is the latest you can search it
here is how it worked for me
grub> set root=(hd0,6)
grub> linux /boot/vmlinuz-5.5.0-kali2-amd64 root=/dev/sda6
grub> initrd /boot/initrd.img-5.5.0-kali2-amd64
grub> boot
here is how it worked for our friend in pervious pages
grub> set root=(hd0,2)
grub> linux /boot/vmlinuz-5.4.0-kali4-amd64 root=/dev/sda2
grub> initrd /boot/initrd.img-5.4.0-kali4-amd64
grub> boot
good luck