Exactly what DarkOne said. The exact same thing happened to me. I lost, 2nd, 4th and reverse one day. under the batter there are two shift link cables. Further towards the firewall there are too brass color forks, that hold them down in a bracket.

My brass fork popped out and was laying on top of the transmission. I put it back on and bam all my gears where back. What causes this?? Probably worn out motor mounts letting the engine move alot and ended up shaking or pulling off that fork.