If you've closed the vim session, its basically gone.
You could have a look for a hidden file ending in '.swp' which is a backup vim uses whilst its running.
Which distro are you running?
Some distros may re-create a basic version upon reboot, based on /etc/udev/rules.d/70-persistent-net.rules or similar.
Ultimately you could try a tool like photorec or testdisk, but its hard work