If you have irregular periods or if you are late are you still able to ovulate?

Yes, you still ovulate, but it is a lot harder to track when they are. If you are trying to get pregnant or trying to not get pregnant, it can be a real bother to plan when you should have sex. This site may help you learn how to track you ovulation cycles so you can better plan when the best time for you to have sex is.
Using Basal Body Temperature Charting to pinpoint Ovulation
Good luck and let me know if you need anymore help or information.