WannaCrypt unlocker is free(?)

[Diggs]

Caveats apply......

http://www.theregister.co.uk/2017/05/19/wannacrypt_key_recovery_tool/
they link to the tool here-

https://github.com/aguinet/wannakey

 

[Galdorf]

Yep it ONLY works if you have not restarted or shutdown the machine chances are it will work in any version of windows.