you may have lost some of your transmisson fluid, just need to see if you have a leak on you gearbox.
normally, gears "slip" if not enough fluid, but when this happened on my sharan,it turned out that before going into gear, i need to apply brake pedal to allow me to move g/lever, when i could not move g/lever i found out that the soliniod under the g/lever cover had gone. very easy to change.
hope it helps, August 2010
