You should never remove a launcher from the phone unless you have another one installed already to take its place, otherwise when you reboot, you will see a blank screen with your status bar and stuck with no way to install another launcher.
You also cannot install system apps like normal apps like you tried, you should have tried to push it back into system/apps and set appropriate permissions using es root explorer, that would have worked. Or you could have used a flashable zip file to push it into system via recovery.

 

Alternatively you could have tried installing some 3rd party home launcher if you can access android market. Can happen to the best of us!