Possible Flash Needed for 7250

[full_metal_nash]

OK here's the deal, i have a Nokia 7250 and i have been told that it has been switched off by the network, so i tried unlocking it and still i had no joy, i spoke to a guy who said i need to change the IMEI Number, i have found the IMEI number but now i need to change the damn thing

anyone got any Links or Knowledge of how this should be done?

Thanks Very much appreciated!