Found old refund check from 1999

[Ellie]

Hello I believe we have gotten a replacement check for this refund years ago. But, on the other hand I cannot bring myself to destroy it just in case. I phoned, they believe it is not one that was replaced, but told me because it was so old they couldn't replace it .... just want to check the laws and if anyone has any information that could help please do so... I was thinking of mailing it in and seeing what happens... but to where?

Thanks!