Nokia 6260 - When I power up the phone, I get the message "App. closed phone" and then if I press OK button, the message "Phone start up failed. Contact retailer" is shown on screen.

It does not take any other keys after this. After sometime the time and date is displayed on the lcd.

Removing the battery, memory card and sim card and re-inserting them does not help.

What do I do to get it strated up again?

you could try a 3 key format (there is a guide in the sticky topics of the 6600 forum that will work) this will wipe averything off your phone memory (not mmc) but it will work better than at the moment!

if that does nothing, take it to a nokia service centre and get it re-flashed.

Nokia 6260 - When I power up the phone, I get the message "App. closed phone" and then if I press OK button, the message "Phone start up failed. Contact retailer" is shown on screen.

It does not take any other keys after this. After sometime the time and date is displayed on the lcd.

Removing the battery, memory card and sim card and re-inserting them does not help.

What do I do to get it strated up again?

try erasing system.ini in your system files. It pretty works for me