1. Start the engine and shift the Honda Accord into "drive." If the Honda Accord won't shift properly, it is most likely due to a faulty shift linkage. While this is uncommon, it can happen on Honda Accord with over 100.000 miles. This is due to the bushings and the linkage itself wearing out from extended use.
2. Let your foot off the brake pedal while in gear. If the car does not creep forward, then your torque converter could be bad. This happens to high mileage Honda Accord. Have your converter replaced by a qualified mechanic. For standard transmissions, you won't have this problem because there is no torque converter.
3. Check to see if your Honda Accord stays in gear while driving. If your Honda Accord won't stay in gear while you are driving, this can indicate a serious problem with an automatic transmission. For standard transmissions, this problem is most likely caused by a worn clutch disc.
This is not a serious issue. However, in automatic transmissions, it can indicate anything from a worn clutch in the torque converter to broken or missing teeth on the planetary gear system that the Honda Accord uses. Have the transmission serviced by a professional mechanic for both issues. source by : http://www.ehow.com/how_5592761_troubleshoot-honda-accord-transmission-problems.html