Sorry about what you are experiencing. I would suggest you to try a password reset to check if you have access to the email associated with the previous account which would solve your issue.
If you cannot recover access through the password reset or other option the best ay is to reach out to the HubSpot support for help on the account and certificates recovery.
If this helps, feel free to mark it as the solution ✔️ and give it an upvote 👍 ! Let me know if you have further questions!