My nokia 7210 is stuck at welcome screeen of nokia and after it turns white screen and continous white screen is their

Usually what causes that is a wire breaking inside of the phone, you can repair it by taking the phone apart, but usually its worth it to just get it fixed or get a new phone, because repairing it can be hard. Sometimes it gets a white screen for another reason though, you can try this to fix it.
Turn the phone off and remove the battery. While the battery is still out, plug the phone into its charger, and turn it on. After you do that, then put the battery back in. It should solve the problem.