cas
Sorry for english
Take a look at
/boot/grub
You *should* have 2 files (back these up somewhere)
grub.cfg
grub.cfg.new
Look at and compare the two, make adjustments or
rename the grub.cfg to grub.cfg.old and rename grub.cfg.new to grub.cfg ** make sure you back up both **
update-grub
If your running a 40_custom compare that to grub.cfg.new and make adjustments
I had a typo in my 40_custom and this fixed it for me
I was stuck on kernel 4.10.6, although newer kernels installed, they didn't show up on grub.cfg and only showed up on grub.cfg.new, so booting up didn't have the newer kernels.
After comparing
grub.cfg.new
grub.cfg
40_custom
and making adjustments all is good
EDIT:
If you don't have both
grub.cfg.new
grub.cfg
perhaps paste your grub.cfg