Replaced the automatic transmission in my daughters 2003 Dodge Neon and it drove fine for about a month and then all of a sudden it would not satart. We replaced the battery, starter and alternator. Don't know what to do next. Considering junking the car. Please help.

Are you saying it cranks but doesn't start? If so, check for codes. It could be something simple like a Crankshaft Position Sensor. Be sure to check all under hood and under dash fuses with a test light or multimeter.