2004 Chevy Suburban Transmission problem

I have a 2004 Chevy Suburban with 48000 miles and today while driving it started making a fluttering/grinding noise from below and then would no longer go. I pressed on the gas and the engine reved up but it would not go into gear. I stopped on the side of the road and popped the hood with the engine still running. No sounds, burning smell, nothing. I laid down underneath it and no fluid or burning smells were coming from it. I shifted through all the gears, but still nothing. I turned the vehicle off and then restarted it. I put it into drive and it started to go. I gave it gas, but eventually after about 200 ft. It fell out of gear again and would no longer go forward.