You are entitled to a copy of the Promissory Note and both sides of the check AND you are also entitled to inspect the originals. It is not clear what court you are being sued in - NYC Civil Court Small claims? Per NYC Civil Court Rule 1101, you can make a discovery and inspection demand under CPLR 3120. If you are in Small Claims, the clerk for that part may be able to give you further guidance.
You are entitled to it under Article 31 of the CPLR. Make a motion to compel production of the documents you want.
I am a former federal and State prosecutor and now handle criminal defense and personal injury/civil rights cases. Feel free to check out my web site and contact me at (212) 577-9797 or via email at Eric@RothsteinLawNY.com. I was named to the Super Lawyers list as one of the top attorneys in New York for 2012. No more than 5 percent of the lawyers in the state are selected by Super Lawyers. The above answer is for informational purposes only and not meant as legal advice.
There is also something in NY called a "Bill of Particulars" which may be used by you to ascertain exactly what it is that forms the basis of their law suit.
The foregoing is not legal advice nor is it in any manner whatsoever meant to create or impute an attorney/client relationship.