Prime Minister Gordon Brown apologized for a potentially disastrous government blunder in which two computer disks containing personal and financial data on 25 million Britons disappeared after a junior government minister said he handed them to a courier service. A government employee has told investigators that he downloaded the personal information, including bank account numbers, addresses and birth dates, put them on two disks and handed them to the courier service TNT on Oct. 18 for delivery to another government office.