HASSos: how to retrieve snapshot from dead installation?

I’m in trouble!
I’m running HASSos under VirtualBox and for unknown reason (I guess for a file system read/write error) my system is corrupted and it’s no starting anymore: well… HASS.io seem to start but no frontend and no addons would start really.
In few words I’m unable to connect with Samba, FTP or whatever to my HASS.io.
I’m able to logged in to the machine and I’ve tried to restore a snapshot but the problem persist; at this point I would want to save my snapshot and start with a new fresh installation… but… how I can save my snapshot on external device?

I guess I must access to the docker image? how to do it?