why, when i turn the key off the car keeps running?

I got a 1997 Buick skylark and I'm having problems keeping it crank my battery good but my dash lights don't come on when I put my key to the on position. ..I no I have a electrical problem..so I try to crank it today it turn over and act like it want to crank so as I took the key out the ignition I heard something kept rattling and it was the starter so the only way it stop I took the terminal off battery..do u have any ideal wat it is