So after finishing several updates to such things as the kernel and graphics driver I left the computer running to go down stairs. When I left it had finished installing everything and was just waiting for me to restart. But in my absence the electricity went out in the house. So although the installation of the updates weren't heeded the computer didn't have a clean reboot.
Steam refuses to come on citing in terminal that it has 'not shutdown cleanly' (Asked on steam forums). My unity panel has changed colour (not sure if one of the updates was for unity) and there seems to be a rather considerable performance regression. Typing ten or so characters into the dash leaves it playing catch up as it fairly slowly displays what I typed and videos seem to play fine when in fullscreen but seem to be every so slightly laggy when not in fullscreen.
How could I fix this? Is it possible to find what packages were updated recently and reinstall them?