Hi there, @Arshad Ali1.
I'm here to help reset your password so you can log in to your QuickBooks Online (QBO) account.
Since you've forgotten your password and no longer have access to the mobile number, you'll need to submit an account recovery form as mentioned by T2_Brooke above.
You can fill out the Proof of identity form through this article and complete the process: Recover your Intuit Account if you can’t sign in. Once submitted, we'll process your request within one business day.
Just in case you want to change your contact info in QBO, you can check out this article for more guidance: Change your business name, contact info, or EIN in QuickBooks Online.
Don't hesitate to leave a comment below if you have other concerns or follow-up questions about this. I'm always here to help.