Do you have this issue only in Sims ? At what point did it go grey ? When you played the game or on the main menu ?
To get out of the game, opening task manager and killing the ts3.exe (or ts3w.exe) process is the only think you can do for now.
Do you have a backup of your save ? What happens if you start a new game for testing purposes ? Is that grey as well ?
Is your family saved to your library from some state ? So you could start over with them at least ?
I don't think there's much that can be done to save the game. Seems like taking the picture corrupted it.
I would suggest making regular backups of your stuff in the future: http://sims3.crinrict.com/en/2011/03/faq-what-files-should-i-backup.html
