T-mobile.com has announced that data saved on Sidekicks "almost certainly has been lost as a result of a server failure at Microsoft/Danger.". According to their press release, they are now trying every possible way to save those stored files but then, they can not promise anything.

T-mobile sidekicks


In addition, they also advised the users to not turn off their gadgets as the remaining files might be lost when they turn it on again. Sidekicks are now tagged as "temporarily out of stock" while this system disaster is not yet solved.

Read more on Engadget