10 years ago? FINRA has what is called an "eligibility" period for claims in arbitration (which yours likely is if you had this stuff in a brokerage account). The eligibility period is generally 6 years from the date of the wrongful conduct. This can, in very narrow instances, be tolled. But I find it hard to believe you didn't at least get a statement of account from your brokerage firm showing that the stock was subject to a reverse split. That would be enough to put you on notice, and likely preclude any legal action on your part.
The foregoing is not legal advice nor is it in any manner whatsoever meant to create or impute an attorney/client relationship.