The shifter needs to be inspected. The shifter assembly is got misaligned, it has to be open and realign.
There are many other possibilities. But if it was working right up till now and suddenly this occurred then its shifter assembly alignment issue.
Also i suggest you to refer these gear shift issues, which are mostly noticed. These are direct links with appropriate solutions to the specific problems of gear ****.
GEAR SHIFT ISSUES
http://howtobyme.blogspot.com/2011/11/chrysler-pt-cruiser-only-goes-in-first.html
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Car is stuck in park and the shift will not move?
http://howtobyme.blogspot.com/2011/08/car-is-stuck-in-park-and-shift-will-not.html
http://howtobyme.blogspot.com/2011/11/car-will-not-come-out-of-park.html
http://howtobyme.blogspot.com/2011/11/automatic-transmission-will-not-go-into.html
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http://schematicsdiagram.blogspot.com/2011/12/car-wont-downshift-sometimes.html
http://schematicsdiagram.blogspot.com/2011/12/buick-park-avenuetransmission-will.html
http://schematicsdiagram.blogspot.com/2011/12/car-transmission-will-no-go-into-park.html
http://schematicsdiagram.blogspot.com/2011/12/shift-indicator-directly-goes-to-2nd.html
http://schematicsdiagram.blogspot.com/2012/01/third-gear-missing-and-engine-losing.html
http://technoanswers.blogspot.com/2012/01/chevrolet-silverado-has-whining-sound.html
http://technoanswers.blogspot.com/2012/01/hard-to-shift-gears-on-manual.html
http://technoanswers.blogspot.com/2012/01/car-hard-shift-at-slow-speeds.html
http://technoanswers.blogspot.com/2012/01/automatic-transmission-shift-lever-hard.html
http://schematicsdiagram.blogspot.in/2012/02/2000-nissan-maxima-shifts-hard.html
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http://schematicsdiagram.blogspot.in/2012/03/vehicle-noticed-sluggish-delayed-shifts.html
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http://schematicsdiagram.blogspot.in/2012/06/2007-hyundai-santa-fe-will-not-shift.html
These details will help.
Thanks.
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