how can i change the number on my apple id cos i lost acess to it

You need to change/add the number on your Apple ID. You may have to add the new number before you can remove the old number. After the change, allow up to 24 hours for the change to sync. Before trying to make the change, sign out of Messages/FaceTime on all devices/computers.

Apple ID - Manage

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If you think your Apple ID has been compromised - Apple ...

~Katana-San~