After I got the Update manger ask me to update the kernel and after restar the only thing I got is a message with:
file can't be found...
and now the only way to boot is to chose the previews Linux in grub menu!
what should I do to fix this?
When grub show up, select old kernel.
Next, type the command below to view / list all installed kernels on your system.
Find the newest kernel than your current kernel. When you know which kernel to remove, continue below to remove it.
Finally, run the commands below to update grub2
Reboot your system