Okay, I understand better now. What you have there is not a Debian install. You have mixed and matched packages and products and have a "frankenbox" that is a mixture of Debian, Ubuntu, and possibly something else with nothing sure to work that would work on any pure install.

In this case I would have made two verified backups before starting to try to install ANYTHING, as well as a recovery and maintenance boot media (USB or CD/DVD) suitable for recovery and restore operations. Since we cannot go back in time, we will have to make due.

Can you make a recovery boot media at this time? If you can, I would see if i could copy the previously used kernel and init image onto it (just in case) and ensure that chroot will work.

I suspect that you may be able to reboot onto the new kernel and get running, but if that fails then you can used the recovery media to recover the system and make such changes as might be needed to fix things.

I have a copy of the entire /boot directory I made a month ago.