Lost my mobile, how can I use my account without the two steps verification?

Try using the Open Get Help app here, and you'll eventually get to chat with microsoft account support.
https://support.microsoft.com/en-us/contactus/

The microsoft authenticator app is not supported here on QnA. They're actively answering questions dedicated forum here.
https://social.technet.microsoft.com/Forums/en-US/home?forum=MicrosoftAuthenticatorApp

--please don't forget to Accept as answer if the reply is helpful--

Regards, Dave Patrick ....
Microsoft Certified Professional
Microsoft MVP [Windows Server] Datacenter Management

Disclaimer: This posting is provided "AS IS" with no warranties or guarantees, and confers no rights.

Hi,

The Microsoft Authenticator App is currently not supported in the Q&A forums, the supported products are listed over here https://learn.microsoft.com/en-us/answers/products (more to be added later on).

You can ask the experts in the dedicated Microsoft Authenticator App forum over here:
https://social.technet.microsoft.com/Forums/en-US/home?forum=MicrosoftAuthenticatorApp

(Please don't forget to accept helpful replies as answer)

Best regards,
Leon

I assume you talk about a work M365 account.

You have to talk to your tenant's global admin for O365. We usually disable / and re-enable MFA again so you can set yourself up again with a new phone number, authticator app, etc.

For next time: use the authenticator app and enable backup to icloud. then you can restore to a new phone. Probably something similar exists for other mobile platforms.

I doubt Microsoft would help or is even allowed to get you into that account by changing the phone number or anything. Anyone could claim to be that accounts owner and the phone is lost, etc. That is the whole point of MFA.