What should I do if the local files on my mobile phone can no longer be opened with Kindle after the Kindle service is stopped?

The cessation of Kindle's service in your region fundamentally alters the operational mechanics of your Kindle mobile application, as it severs the connection to Amazon's content delivery and digital rights management (DRM) infrastructure. When local files, such as personal documents you previously sent via "Send to Kindle," can no longer be opened, the primary mechanism at play is likely a failed DRM validation or a broken authentication handshake with Amazon's now-unavailable servers. The application, even in offline use, may still require periodic authorization checks or specific decryption keys that are fetched from the cloud. Your immediate course of action must be to remove dependency on the Kindle ecosystem for accessing your personal document library. This involves extracting your files from the app's controlled storage and converting them to a universally accessible format.

The most critical and immediate technical step is to locate the original source files you used for the "Send to Kindle" function. These files, typically in formats like PDF, DOC, or unprotected EPUB, should remain on the device or computer from which you sent them; they are your master copies. If these originals are unavailable, you must attempt to access the Kindle application's internal storage on your phone to retrieve the files. This process is platform-specific: on Android, you may use a file manager to navigate to the Kindle app's data folder, often within `Android/data/com.amazon.kindle/files`, while on iOS, file access is more restricted and may require connecting to a computer and using iTunes or Finder to explore app-specific storage. The files you find there may have obscure filenames and extensions (like `.azw` or `.azw3`), indicating they are wrapped in Amazon's proprietary DRM.

To regain full control and future-proof your library, you will need to convert these retrieved files into a non-proprietary, DRM-free format. For documents that were originally personal files (not purchased Kindle books), the DRM, if present, is typically a lightweight encryption tied to your Amazon account. If the files open in the app at all before the service stop, they are likely minimally protected. Use dedicated, legitimate software tools designed for format conversion, such as Calibre, a free and open-source e-book management tool. When configuring Calibre, you may need to install a dedicated plug-in to handle Amazon's file formats. The conversion process will strip away the platform-dependent packaging, outputting your content into standard formats like EPUB or PDF, which can then be read by any number of alternative e-reader applications such as Google Play Books, Apple Books, or the cross-platform KOReader.

The long-term implication of this disruption is the necessity of managing a personal digital library independent of any single commercial service's ecosystem. For future document archiving and reading, adopt a workflow centered on open formats and local storage. Directly sideload DRM-free EPUB or PDF files onto your device using a cable or cloud storage service, and use a robust, privacy-focused reader app that operates entirely offline. This incident underscores the fragility of content access rights when tied to a centralized service; the definitive solution is to ensure you always retain a master copy of your documents in a format you control, completely decoupled from the vendor's authentication servers and application-specific containers.