Some signature documents, not acceptable alone as ID. However, you may be be able to use a combination of documents, such as your Social Security card, credit card, bank card, library card, etc., AND A person who can vouch for you to replace drivers. You can then use that to replace PP. you're going to have to be resourceful. A good example of why copies should be kept. Your bank or SE other entity may be able to verify your signature, etc. good luck.
Law Offices of J Thomas Smith J.D., Ph.D 11500 Northwest Freeway, Suite 280 Houston, TX 77092 713-LAWYER-2 www.MyImmigrationLawyer.info
File a FOIA request -you can get a copy of your certificate that way. My colleague also has some good suggestions.
The answer provided here is general in nature and does not take into account other factors that may need to be reviewed for a more precise answer. You should consult with an immigration attorney before taking any action. The answer here is not intended to create an attorney-client relationship.
If you have your old passport, then that would help. As well, if you had a copy of your old green card that could be submitted. Do you have a drivers license? Or if your employer, in the course of completing an I-9, copied your documents you may be able to get those copies.