What would happen if I switch the positive and negative inputs of a inverting amplifier ( - to GND and + to input and feedback)?

 

The output would go high to the saturation voltage and stay there.

 

You now have a non-inverting amplifier with positive feedback. This causes the output to saturate as Eric noted.

 

There is a non-inverting amplifier configuration for opamps, if that is what you are looking form. Google it.

Bob