Sorry that Photoshop CS6 crashed and you can no longer access the file you were working on.
Photoshop saves a copy of your file in the background if auto-recovery is enabled in preferences. Did an auto-recovery file opened up when you launch Photoshop post the crash happened?
Please refer this articleTroubleshoot file recovery in Photoshop and let us know if you're able to recover the lost data?
The lesson learned here: always save your work in steps and with different filenames (versions). You can't trust software not to crash. Do not rely on a software's automatic backup or auto-recovery feature. Those are last-line defense measures.
Save your work. Save often. Save many versions. And create backups on an internal and external drive.
Which operating system?