Why my nikon battery charger is not blinking?

I didn't recharge for three weeks, two days before i took the photo with that battery, and atlast my battery gets drained out and am connecting the battery to the charger its not charging what's the problem.

can i charge for more than 5 hours continuously

The battery should recharge in less than two hours. Maybe the battery is worn out?

Vinegar Taster is right.

There's a high probably that you damaged the battery by letting it sit discharged for over two or three days.

Li-ion batteries need to be stored for long periods of time only when they have a good charge on them, 1/2 or more.

It is highly unusual for an Li-ion battery to fail if it is properly manintained. I have some that are over 10 years old and they are still able to take a full charge and last for 1000 shots or more (D300)

If your battery is still under warranty, call Nikon for help. 800.NIKONUX

You could have a bad charger. My brother's D40 charger lights are kaput, but the charger still charges the battery normally. You can leave the battery on the charger for days without problem. Li Ion chargers are designed to safely leave the battery in the charger for extended periods of time. Charge the battery and see what the charge indicator on your camera says.
If it doesn't charge the battery, time to give Nikon a ring if it's in warranty.

Next time, don't fully discharge your battery. It will get you in to trouble (dead batteries when you really need to take that cute shot of your kitten is a sad moment).