Recover Yahoo mail account lost sim

Hello,
hi i just want to ask how can i open my account and my children's account,we haven't logged in for quiet sometime and unfortunately when we logged in we have to verify using the registered sim(cellularphone)the problem is that sim was stolen together with the cellularphone.how can we still open it...
i badly need to retrieve my children's account because I used to email there the special occasions of their lives(i created that when they are still babies) and now that they are grown up,i wanted to share all the memories i had kept in their accounts...hoping that you can help me retrieve our accounts.GB