I appreciate the steps you've taken to recover your QBO Accountant account, Ashraful. The error occurs if your credentials aren't linked to an active product or if the account was deleted due to a prolonged period of inactivity.
To further investigate on this matter, I recommend reaching out to our Live support team. They have the right tools to help you check if your account has been deleted and tell you exactly when it happened. Please ensure to check their available hours to ensure you get in touch with them at the right times.
You can also read this guide to keep your login information safe: Update or change your Intuit Account sign-in information.
Please don't hesitate to reach out if you have further concerns. We're here to assist further.
