Ubuntu mistakenly deleted the kernel boot file under /boot, causing it to fail to start now? How can I recover?

  linux, question

I accidentally deleted the kernel boot file when cleaning up /boot space yesterday. Now I can’t find the way to start Ubuntu in the grub boot entry. How can I fix it?

Start a liveCD or a temporary linux environment, mount all partitions of your original ubuntu into a folder, for example, ubuntu has only one/mount point, mount to /mnt/ubuntu, and then chroot into this folder to try to rebuild the boot.