(AP) -- There may be a happy ending after all for owners of Sidekick phones who thought they might have permanently lost contact numbers and other personal information they had put on the gadget.
Earlier this week, T-Mobile said information stored by many Sidekick owners was "almost certainly" gone for good following a failure of the computers that remotely stored the data.
But Microsoft Corp., whose Danger Inc. subsidiary makes the phones that are sold through T-Mobile USA, said Thursday it recovered "most, if not all" of the missing data and will restore it as soon as it validates the information. Microsoft also apologized for the glitch.
Sidekick service was intermittent last week after the data outage, and after that users began reporting that their personal information had been erased from their phones.
On Saturday, T-Mobile and Microsoft warned customers not to restart their phones, take out batteries or let the phones' batteries run out. The Sidekick's underlying data services were working by Monday, but T-Mobile still suggested then that customers refrain from resetting their phones.
T-Mobile issued customers a $20 refund to cover the cost of one month of data usage on the phone and said it would give customers who experienced a "significant and permanent" loss of personal data a $100 customer appreciation card they could use for T-Mobile products and services, or their phone bill. T-Mobile said it would contact those customers in the next 14 days.
In an open letter to Sidekick customers Thursday, Microsoft said it would "work around the clock to restore data to all affected users, including calendar, notes, tasks, photographs and high scores, as quickly as possible." The company added that it believes a "minority" of Sidekick owners were hurt by the loss of data.
It isn't clear how many Sidekicks are currently used by customers; judging by T-Mobile's financial statements there could be nearly 1 million.
Microsoft said that a computer system failure caused the loss of data both in a core Sidekick database and in a backup database. The company said it made changes to improve the Sidekick service's stability and the backup process.
T-Mobile spokesman David Beigie said the company was pleased that Microsoft and Danger are making progress on recovering the data.
More information: Sidekick's lost data gone for good
©2009 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.
Explore further: Emerging world drives cheap smartphone boom