The company has created a special support website for the recall where customers can enter their iPhone serial number and see if their phone is one of the "small percentage" of iPhone 5 models that are affected.
Affected phones can be brought to an Apple Retail Store or Apple Authorized Service Provider, though the phone will need to be sent to an Apple Repair Center for servicing. Stores will have some iPhone 5 16GB models available as loaners. Another option is mailing the iPhone to Apple, with details available on the recall program's website.
Replacement of the sleep/wake button mechanism is done at an Apple Repair Center. There are two ways to send your iPhone to the repair center—carry-in or mail-in. See below for details. The replacement process takes approximately 4-6 days from the time your iPhone is received at the repair center until it is returned to you. Your iPhone will be examined prior to any service to verify that it is eligible for this program and is otherwise in working order. Before sending your iPhone to Apple for service, you will need to back up all your data and erase all your content and settings.
Users who believe they have paid for an out-of-warranty replacement to rectify this issue should contact Apple regarding a refund and the company notes that this does not extend warranty coverage for any other issues. Additionally, the program is only effective for two years after the initial retail purchase of the iPhone 5 unit in question, meaning buyers who purchased the iPhone 5 when it first was released have at least five months to have their machines repaired.
Apple requires that any phone that receives a Sleep/Wake button replacement under the program be upgraded to iOS 7.
Source : macrumors