You might need to find a combo update and try installing that : http://www.apple.com/support/software/
If you use time machine, roll back to the last update before your problem and restore from there or simply find what you were updating and install the last good back up of that then re-update.
Just remember to plug it in this time!
If you do do a restore from a previous good back up, then burn any documents, music etc to a disc first before hand so that you will not loose them after a restore.