If you've lost both then you're likely to be aware of that and can cancel stuff
If you haven't got your phone, and like many people, you keep your life on it, you won't even be able to get the numbers to contact your banks(s) etc without going to a computer to dig out all the info.
Then you'd need access to a phone to make the calls.
I keep all info, including recto/verso copies of all my bank cards etc, on a Dropbox document, and a hard copy in my safe. I realised that there is a risk in that too, but few things in life are risk free.