I've just had the same problem! Seems that it is a common problem with Nissan Micras. I needed a new motor for the handle, so best bet is to take it to a repair shop.
Kiase
March 2012
spray wd 40 into key hole and wriggle key till it releases tumberlers in lock and key turns
howtomendit.com for free repair help, information and advice.
Try fixfault.com to fix cars.