How can I unlock my account if I don’t have my number anymore

Your number should not be necessary to unlock your account. If your Apple ID is using Two-Factor authentication, then the code should be received on a device that is logged in to the account or a phone number you set to receive it through voice calls or SMS. This phone number should obviously not be your own phone number from your iPhone, it can be a land line or even a friends or relatives Android phone if necessary.

If you don't have another device to get the code on and for some reason you set your own number as a trusted phone number for Two-Factor Authentication, then you need to go through the recovery process.

How to use account recovery when you can’t reset your Apple ID password - Apple Support