crayb:
The door latch (the D shaped ring on the door jamb) is adjustable. Perhaps it has come loose. The dealer should be able to adjust it for you.
tbianco:
Nissan released a tech bulletin regarding doors that fail to open. There is an issue with water getting past the door handle seals and freezing inside the mechanism. Once this happens, the door no longer operates. Nissan will repair the latch under warranty and install new door handle seals and grease to keep it from re-occuring.
Schedule an appt. with your dealer ASAP.
NTB09125 - CP 2008 - 2009 Rogue; Front Door Handles - Voluntary Service Campaign
In certain 2008 and 2009 Nissan Rogue vehicles, to assure customer satisfaction, Nissan is conducting a voluntary service campaign to install seals to the door latch assembly and apply special grease to the door cable ends to prevent freezing under certain conditions. See this bulletin for further details.