Computer wont restart properly

[stevef]

First off, if you don't already have copies, use the live boot to recover to a safe place all important data that you need from the installation that won't boot.

Once that's done, if you were using a system backup/recovery tool like Timeshift on the system you can attempt to roll it back to previous states to see if the problem resolves.  The method will depend on what backup/recovery schemes you have.

If that's not an option, you may need to try a fresh install.  If the fresh install boots ok, make a system backup before doing any updates.