Relaunch the Mac OS X Finder
Generally if you kill the Mac OS X Finder it will automatically restart itself. Generally. When the Finder doesn’t auto relaunch, you can manually launch it by using the Terminal and the following command:
open /System/Library/CoreServices/Finder.app
The Finder will open and things should be back to normal again. If the Finder still doesn’t launch, you may need to reboot your Mac to get everything back in order.

Finder always relaunches for me after a killall but a kill -9 seems to prevent it doing so.
What about just clicking the icon in the dock?
I just click the icon in the dock

(Why geeks always look for complex solutions? It is a Mac, not a PC…)
`open -a Finder` also works.