I didn't install a kernel and I didn't remove anything but update-grub did
remove some lines in the grub menu. These may have been older kernels but I'm
not sure. I just installed Trisquel some days ago, so I wonder if there
should have been an automatic kernel update this soon?
In the grub menu I automatically get the option to choose 'Advanced options
for Trisquel GNU/Linux' but entering them leads me back to the grub menu.
Actually I had the same issue when I first installed Trisquel. I fixed with a
clean install.