Stuck on Fn mode,sony vaio

My cat has walked across my keyboard and clearly pressed some combination of keys. The result is that the keyboard now only recognises the orange command under the white main command e.g uiop (white command keys) will appear as 456*. If I press the Fn key it corrects to the white command key. I'm assuming the Fn key is operating as permanently depressed but don't know how to revert to normal mode.

Any help greatly appreciated.