There probably will be just be a judgment against you for the ticket amount due to your failure to show up. Go to court on Monday and try to straighten it out, but do not expect the court to cut you a break. Still, you should try. It might work. Your options depend upon what happens on Monday. You might just want to pay the ticket, as it is an infraction and not a criminal record.
You need to go to court first thing Monday morning and add yourself back to calendar. Find out if you have a conviction for the infraction. Each county has a different procedure on how you can add yourself back to calendar. Be prepared to explain to the court why you missed your last court date. If you ended up with a conviction for an infraction and the court agrees to set it aside, you can then go on to present your defense, including your medical marijuana card. However, none of this applies if you were charged with a misdemeanor. If you were charged with a misdemeanor, you should definitely seek counsel before you pursue this yourself.
This answer does not constitute legal advice and does not create an attorney-client relationship.
If this is Van Nuys there might also be a warrant or civil assessment against you. You need to go to court Monday and straighten this out. Go to clerk on second floor and find out where it stands.
Andrew Roberts (818) 597-0633/ (805) 496-7777