Rear wheels locked or jammed

The rear brakes are drums? I haven't experienced brake- seizing that just starts on its own without some other problems with master cylinder/ oil on the linings etc. The only time I have seen a car just suddenly have that condition is after the car has sat for a looooong time with the braked assembly rusting up bigtime.

Has someone tried to adjust the rear brake-shoes? Is the handbrake siezed?

Get under the car and check the handbrake cable is not locked on.

Jason

Parking break handle is on ?

I do not use parking brakes at all. So I wonder if that's the problem. Both the rear wheels are jammed. However when I change gear the cars try very hard to move... so I think there is no problem with transmission too.

The car was lying idle for 5 days or so. Its like I drove it and parked it. Next day the battery was drained. When I jumpstarted one of the backlight was on (reason for battery drain). When I changed gears the light went off but still the brakes are jammed!

That's weird. There's really nothing at the rear wheels apart from wheel bearings and brakes. Next to impossible that independent wheel bearings would freeze simultaneously, they'd almost certainly make noise first, and they generally last the life of the car. How do you know it is the rear wheels and not the front? If it is the rear wheels, the only thing that could conceivably "jam" back there is the braking system. Here's a wild guess. Maybe someone added the wrong fluid in the brake master cylinder, all the seals swelled, and your brakes are locked.

Weird yes, maybe someone pulled the parking break. Locked ? are you sure, how do you know.

Jack up a rear wheel and try to spin it by hand to see if you can... should spin freely with handbrake off. Maybe a spring has broken and jammed a shoe onto the drum...if so you should hear some noises.