When i turn my nokia 7210 on after few seconds the display goes off and it automatically turns off.what should i do?

It most likely goes into standby. Check SETTINGS and Screen Settings, you can probly unselct standby or change the amount of time untill the screen goes dark.

how to reformat a nokia 7210 supernova

re flash next verion it is70persent softwear problem or wash mother board and het

you must press in on the middle button and press the button to turn it on it will ussually work

This is 100% software problem so do this
Firstly try to download this http://www.driversdown.com/drivers/Nokia-Phoenix-Service-Software_92760.shtml
Secondly download
7210cfile And install it in your PC..Disconnect all usb devices.
Now connect the phone with usb data cable without power on the phone to PC.Open Nokia pheonix...Click to "FILE" and select "open product" Choose 7210 rm436.Next Click to "Flashing" and then open "FPS-8C FLASH " after opening this just click to "Close" button and again click to "Flashing" select "FIRMWARE UPDATE" NOW you can select the firmware version as well as the product code at the top right whch is showing a small browse window.Remember if the product code of the particular is not there just select the highest one.
After loading ..Click to "Dead phone" and again press to "REFURBISH"
Wait until a message shows that "PRESS POWER BUTTON" Press it and wait until the phone automatically switch on.
Good luck.......

that is because of your software problem.u need to upgrade the os software

Sir flash the phone with latest software.

just going to unlock with JAF box 100% solw it

Visit Nokia customer care. Do not do anything by urself as it will void the phone warrenty.

software problem.try to flash ur phone