99 Honda Accord

The first signs of trouble was driving it on the highway for about 20 minutes and upon coming to a stop light and trying to accelerate the car wouldn't go. Shifted to natural and back to D4 tires spun but finally the car took off... let the car rest a few days and drove it literally around the corner to Orileys and got code "P0730" let the car rest again a few days around the block a few times. It again seemed to knock out off gear. When I got home I put the car into reverse and parked and cut the car off.. now when I put the car in ant gear the car just rolls backwards. I just purchased the car on last Friday. Not sure if it's worth stating but every light works except when it's in D4. Please help?