All may not be lost.
There are several Do's and Don'ts as regards US Copyright Law. Have a look at the RPMDA (Retail Print Music Dealer's Association) website. There are two clauses there that are interesting to note.
Under the heading, What You Must Not Do, the first item states that "Copying to avoid purchase" is expressly prohibited. Well, if you brought a manuscript into the SF Music Library and wrote out one of your old scores in your own fair hand, or if you borrowed it and photocopied it at home, you would be not be avoiding purchase. You (presumably) previously bought that score. It's simply not in your keep. You had donated it to the Library.
Under the heading What You Can Do it states that "Emergency copying to replace purchased copies which for any reason are not available for an imminent performance provided purchased replacement copies shall be substituted in due course". Well, this is an emergency, is it not? The original purchased copy is currently unavailable your Honor, but I hereby swear that I did purchase the score, and furthermore, Judge, I can produce the said copy, once I have renewed my Library Subscription. Sheriff, take him down .....