2004 Ford Expedition

It has the 5.4 L V8, push button 4 wheel drive, all leather heated seats, the pull down DVD player, almost new tires, new plugs and coil packs, new trans fluid and filter, and runs perfectly. But after the fluid, filter change on the transmission... It won't go in drive!? It will go in reverse in two wheel and four wheel drive but I have no forward gears. Still a very solid vehicle. Only serious inquiries, please! Will negotiate or consider trade... Or if anyone knows where I can get a used transmission for fairly cheap to install myself. Or... If someone has any old wise advice as to what might the problem be. It never made a noise, it didn't slip in and out of gear, it simply just will not go and drive but has all reverse, four wheel and two wheel.