Now my Conversation doesnt shows anything in it. If one SMS come it, I can open and read. But if 2 SMS received and on the notification yellow box stated 2 SMS, if I touch the box, Conversation open, both messages gone. I can send SMS thru Phone but the history show last SMS was 29th Dec. After that all messages are not stored.
When I reboot, any sent SMS, a delivery notification are shown again and also all SMS received earlier also got notifications but when open, they all vanish.

Anyone can direct me to how to reflash or reinstall M5 to my N900? The missing SMS and IM are very annoying.