It's up to you as to whether you wish to pursue this in Small Claims court. Since you haven't mentioned the amount they kept out of your security deposit, we have no idea if this is worth your time or trouble to do this or if you should attempt this simply on principle.
Typically filing for Small Claims is not very expensive and you would represent yourself in this court.
Your argument in court to justify your lawsuit would be to cite the landlord tenant law in your state that because the landlord failed to provide you this information within the required time period, they now owe you your entire security deposit.
You might try writing your former landlord a "demand letter" first, citing this statute (provide them a copy of it) and stating you want the entire deposit back or you are considering a lawsuit over this matter. Give the landlord a deadline (say, two weeks after they receive the letter) to return the full deposit to you.
In the meantime, if you wish to continue this, hang on to the check you received and don't cash it.
Gail
