05 Nissan Altima...possible tranmission Problem..HELP

[duranmc]

So I was driving my car the other day and all of a sudden when I went to hit the gas the car wouldn't go...(Engine didn't shut off, it just acted like it was in park) The Car only moves in 1st gear and reverse....05 Nissan Altima....any ideas what it could be.....The engine light is not on and neither is the transmission light..(although I know you can't rely on the lights)..I just replaced the crankshift position sensor....It is an automatic car, 4 cylinder, 86000 miles...not making any weird noises

Any Suggestions...do you think I will have to get the entire transmission replaced or could it be something else...Just need some ideas before I bring it to the mechanic

Thanks again in advance!

[duranmc]

I also had the crankshaft position sensor replaced a week ago...although I don't think it has anything to do with the problem