When you have a lot of text selected which you have kerned and/or tracked out and you simply want to reset all of it to zero, you can either go to the tracking and kerning input boxes in the Control Bar and do it manually, or you can do it the easy way.

With all your text selected, simply hit Command (Apple) + Option + Q. All your kerning will return to normal. Don't you just love keyboard shortcuts! This works in Adobe CS2 and CS3.