If a website has been hacked or lost we can sometimes recover the content from cached Google pages, the “Wayback” archive or old backups.
We can sometimes recover data from a crashed or hacked computer. To increase the chances of successful recovery you should stop using your computer immediately and turn it off because in this situation every time a computer saves data it might be overwriting good data with bad.
Note that disk recovery can be a very time-consuming process with no guarantee of success, because the recovered files may be in small chunks with no filenames. It’s far better to have good backups in the first place using a service like Crashplan.