Grinding in reverse car will not Move

My car had been running great then one I parked my car after driving fine on the highway and I heard a noise that made me think the axles were going out. Then a little while later I tried to start it, it sounded fine until I put in reverse, it started grinding and and got so loud I thought it was going to explode so I turned it off. Two weeks later started it again sounded fine put it in reverse no grinding noise, but it would not move at all not even when given gas. I went to put it in park and it acted a little funny and the lights on the inside flickered a little, I was able to put in park and turned it off. What is going on with my car?