Mobile number change

Hey guys (this is my 2acc) I recently changed my number and forgot to change it for the authenticity which is why I am now locked out of my account I had it Tried to change the number on my Instagram account but to change it I have to access my old number I ignored it for a while but today I had a Meta Quest 3s Bought and wanted to log in with my account but it's just not possible so what do I do now I have no access to anything except my Instagram