If you haven.t already upgraded to SSMS 2016 you should do immediately. The guys at Microsoft have decoupled SSMS from the SQL Server release cycle and one of the best features by far is the auto-save\recover functionality.
Remember all those times you were putting the finishing touches on the best code you’ve ever written and SSMS crashed? Well worry no more. I did post previously about how SSMSBoost can help you to recover recent sessions, but now SSMS does it out of the box.
When SSMS crashed you’ll be asked to recover recent work and will see something like the below:
All you need to do is connect them back up and viola you’re away!
Of course you could always (and you should always) save your work as soon as you create a new window, but who am I to tell you how to live your life….