This really depends on your location.
Were you returned your security deposit in full or was there actually some money missing? If money was missing were you provided with a receipt listing the damages causing the deposit to be short? How long after your lease terminated did you receive this?
How long is a while ago?
If you dont show up to the small claims court case the judge will in all likelihood award a default judgement against you in the full amount you are being sued for. Have you attempted contacting the party that is suing for you and offering a sttlement for them to drop the case? IE write to the guy suing you, say "Hey we dont need to go to court over this, Ill agree to pay if you drop the case. I dont have time for it."