Problem with charging nokia 5800

Buy new mobile .........

If your phone was bought in the last 6 months you can go to nokia care center and demand for a new battery and charger or repair the existing ones provided you have the warranty card.You should get it done for free of cost.If 6 months exceeded then

Did u try another charger of the same mobile company,if yes ,and it works ,the problem is with your charger.You can either buy a new charger or get an all battery charger ,a china piece that recharges all batteries of any mobile company.You can get it below 2$ .
If your battery doesn't charge even with other charger of the same company then the problem is with your battery.If you are a nokia user ,here is the price list of all nokia batteries.
http://www.priceindia.in/mobile-phone/nokia-battery/

I had the same problem. Try taking the battery out and putting it back in. This worked for mine and it immediately rebooted but was thinking I might take it back into the shop as I'm sure this shouldn't be happening.....