Try your linkage first
You could trawl through old posts on here from about 2 years back as I had the same trouble but in essence...
http://index.php?topic=2375Get under your car at the bottom of your gear stick. It should attach to the shaft going into the transmission
If it doesn't, you should be able to engage it fairly easily - I did it with one hand - as a temporary fix. A more permanant solution requires work well beyond my feeble brain, other than i know my temp fix got me to the specialist who repaired it. Common in cars that sit in traffic a lot, apparently....