Today my wife went to back out of the driveway and shifted into reverse, stepped on the gas and it moved a couple feet then there was a bang from under it and now it wont move in drive or reverse and makes a grinding noise when put in park. any ideas please help.

 

Get it to a transmission shop as soon as you can. Probably will need to tow it. Since you don't tell us what year, engine, mileage, or anything like that, we can only guess. Do us a favor and put your vehicle info in your signature. Narrows down the guesses. What does the fluid look like? What's the fluid level?

 

I simply echo jkeaton's suggestions and questions. Definitely take a look at the fluid.

Have you had a chance to get it to a shop (dealership or otherwise) yet?