I forgot the combination - Targus Defcon CL Security

Hey man, im not sure there is a way to reset it without knowing the combo first.
however, i did find a very detail video on how to figure out the code. if you go to

http://www.engadget.com/2006/09/08/the-lockdown-your-new-targus-defcon-cl-lock-hacked-by-beer/

and scroll down to the bottom, there is a link to a video you can download and watch that shows you step by step how to solve your problem. the video link is in blue and starts with the words "as shown in the video".
hope this helps

This won't work for the locks with the off white plastic which don't have the same small flathead screwdriver end thing.
This video I found helped me unlock mine (by feeling for the stop points a specific way) in a few minutes after watching the video and trying it out.
It was surprisingly easy.
video direct: https://33ad.org/tmp/onr/defconcl_vuln.avi
post: http://www.lockpicking101.com/viewtopic.php?f=3&t=48865