back door wont lock with or without key or lock buttons

It may be disconnected linkage inside the door, but this is going to require removal of the door panel to see what is happening. Get a good repair manual if you are going to do this yourself: http://bit.ly/mitchell_repair_manuals_online Or find a shop to do this for you: http://repairpal.com/toyota-repair-in-holtsville-new-york