Reclaiming Unclaimed Funds from a Closed Bank Account

About 10 years ago, I closed a bank account and received a cashier's check, which I never deposited. Unfortunately, I've lost the check. Recently, I've been receiving letters from a lawyer claiming they can help me access this unclaimed money if I sign it over to them. I'm wary of this being a scam.

I've contacted the original bank, but they say they have no record of the account since it was closed 10 years ago. Does anyone have advice on how to reclaim this money without falling prey to scams? I'd appreciate any guidance on the process.

Acknowledgment: I used ai to edit this post because was all over the place and way too long. I know it sucks, sorry. I just want to be clear and get good advice.