accidently installed update

[npm1]

Long story short.
how do i reverse the update i made to a perfectly working 10.8.3.

MY Story.
I went to the app store clicked on the updates and chose the 10.8.4 update, a prompt came up asking for a restart, but I accidentally clicked on restart
then suddenly a box came up with the default mountain lion login window wallpaper.
the box had a count down with a progress bar eventually it was at 10 seconds,
then suddenly it said "error, please restart(or something similar)"
So now i'm left with a hackintosh laptop that won't boot and is stuck on something.....

How can restore my previous osx without loosing the data thats on it.

PLEASE HELP

 

[UrbanBard]

Simple. Easy. Use Time machine restore.

Install your USB Bootloader on computer, reboot, select your USB rather than HDD. Rather than reinstalling OS X software, go up to the menubar where Disk Utility is. The bottom entry is "restore using time machine."

Select a time from just before you uploaded. It will take about an hour to restore your system to what it was before.

If you want to upgrade, download the combo installer from Apple.com.