lost 2nd step verification device

My daughter cannot sign back into her Apple account. Which means she can’t use anything on her phone. She signed out of it and then when she tried to sign back into it it wanted her second step or factor whatever thing verification. She no longer has access to that laptop that she was using as her second step. How can I get her logged back into her Apple account?

BTW, not sure what iPhone 7 level it is.