Camry doesn't move after pressing accelerator

My Camry doesn't move forward after pressing the accelerator. The Check
Engine indicator is on. My car was running just fine when I last parked in my
underground parking 3 years ago. I then went out of country on a 10-month
project but actually returned after 2 years. My car battery was down. Since it
was quite old I replaced it with a new one. But then my car didn't move my
after pressing the accelerator I noticed that the check engine indicator is on.
The Owner's Manual mentions, "If the engine speed does not increase with
the accelerator pedal depressed down, there may be a problem somewhere
in your electronic throttle control system." Any idea what this problem could
be? Can it be fixed by opening the hood (and in my underground parking) or
I have to tow the car to a mechanic because it requires a car lift? I hope
nothing has happened to my transmission.