I would suggest you have the fluid & filter changed. If this does not solve the problem which I suspect it will, seek professional help.
There are several things that can cause your Honda Accord station wagon automatic transmission not to shift down. The most common cause is low transmission fluid.
dirty tranny fluid
A bad transmission gear can cause your 1999 Nissan frontier to shift hard. Low transmission fluid can also cause the transmission to shift hard.
A seized up transmission can cause a Volkswagen Golf with an automatic transmission to not shift and racing RMPs after second. A worn gear can also prevent shifting.
Linkage adjust
Auto? Low or dirty transmission fluid? Plugged filter? Bad transmission pump? When my husband's car wouldn't shift (it was an automatic) it was his crankshaft sensor. It ran fine after that.
You can't shift gears on an automatic transmission because, as it is called, it's automatic! You don't need to shift, it does it for you. == == Maybe the question should be "Why is my automatic transmission not shifting through gears for me as it should?" Could it be a fairly simlpe fix or am I losing my transmission? Yeah Dopey!
you have to put your foot on the break pedal, to shift out of park its a safety feature
check the shift linkages for adjustment.there is also an actuator switch on side of transmission will prevent this. if those 2 checks dont fix the problem, your transmission is shot
clutch plates could be welded to gather
if it is automatic then this would be caused by shift down is not working in transmission
A bad first speed overrun clutch.