Transmission problems are one of the most expensive and dreaded vehicle repairs that car owners have to make. Replacing or repairing a transmission can cost several thousand dollars and typically requires a specialised mechanic who deals exclusively with transmission work. The linkage in your transmission is what enables your vehicle to change gears when you tell it to.
If you try to put the vehicle in gear and it won't go or nothing happens, there is a good chance there may be a problem with your transmission linkage. If your linkage is broken or disconnected, the transmission will not receive your signal to go in gear. Therefore, you may shift your shifter into drive, but your vehicle will stay in park.
Car Won't Start
Your car is designed so that it will start only in certain gears. If your transmission is not in park or neutral, your vehicle will not start. If your transmission linkage is not working properly and your transmission did not actually go into park when you put it into park and turned it off, then the next time you try to start the car it probably won't start. You may be able to get it to start by moving the shifter through the gears a couple of times and then back into park.
Generally speaking, you should not be able to hear your transmission. If your transmission is making a loud clunking noise when it goes into gear, there is a good chance you have a problem with your linkage, or the bushings that control the linkage. Clunking, griding and any other noises should be checked out immediately by a transmission repair shop so that problems can be fixed before they become serious enough to stop the vehicle from working or require a complete transmission rebuild.