Car will not drive forward do you know what could be the problem

Check the fluid leavel and condition if okay-bring it in and have it checked for slippage and pressure tested-

You can try the filter replacement don't work get it further checked-

Just to add to this one there is no filter you change for maintance it only has a internal filter and you would have to split the case to change it. Those transmissions are junk I have rebuilt and replaced so many I lost count. It most likely needs a side cover that contains the input and output shafts the belt etc you would also replace the internal filter. Flush the transmission cooler and replace the transmission cooler lines. Before doing that you need to check the transmission pressures which takes a special gauge because that transmission runs at extremely high line pressures over 600psi. It also takes a tech2 scan tool to command the line pressure actuator to the differnt amps to check the pressures. You have to check the pressures to make sure you dont have pump or valve body issue that caused the side cover to fail. It doesnt take a pump or valve body issue to cause them to fail though. Thats what I would do to repair it though really common for them to do that. Also a very expensive repair it also takes a special fluid and additive in the transmission. Wish I had better news for you.