Lost many data after an update! Please help

Please check the following (It's important to note that none of the suggested solutions are related to an iOS update.)

1. When you create a backup of your iPhone using iTunes or iCloud, it captures a snapshot of your device's data at that specific moment. If you later delete any data from your iPhone, such as photos, messages, contacts, or any other information, and then perform a new backup, the deleted data will also be removed from the new backup. The backup process essentially reflects the current state of your iPhone, and any changes made to the data will be mirrored in subsequent backups. So, be cautious when deleting data from your iPhone, as it will be permanently removed from future backups as well. If you wish to preserve specific data, it's important to keep it on your device until after the backup has been completed. Backup methods for iPhone, iPad and iPod touch
2. If you sign out of Apple ID sign backing with another Apple ID after you had turned on Messages in iCloud & iCloud Photos, your content is safely stored in iCloud and is available on all devices that use the same Apple ID.
3. If you have restored your iPhone with a backup that does not contain the Photos that you are looking for then please look for the correct backup on your PC/Mac --> Locate backups of your iPhone, iPad, and iPod touch - Apple ...
4. Do you have a correct backup (iTunes) --> Restore your iPhone, iPad, or iPod touch from a backup ...
5. If you have restored from iCloud backup, then note the following
   1. iCloud backup doesn’t include information that is synced and stored in iCloud, like Contacts, Calendars, Bookmarks, Mail, Notes, Voice Memos, shared photos, iCloud Photos*, Health data, call history, and files you store in iCloud Drive.
   2. *-If you had turned on iCloud Photos, your content is automatically stored in iCloud and is not backed up.
6. Probably you may have un-synced photos with Mac / PC, sync them again
   1. For PC: --> Sync photos in iTunes on PC with devices - Apple Support
   2. For Mac --> Sync photos between your Mac and iPhone or iPad - Apple ...
7. Have you ever imported your photos to Mac/PC and used "Delete After Import" --? Transfer photos and videos from your iPhone, iPad, or iPod ...
8. If not found anywhere, have you ever uploaded them to any Cloud Drives (iCloud Drive, Google Drive, OneDrive, DropBox, Flickr, box, AmazonDrive, Adobe Creative Cloud etc)

Updating iOS on your iPhone should typically not alter the fundamental functionality of the device. It's possible that there were underlying issues before this update, which you might not have been aware of previously or might not have noticed.

In general, iOS updates are designed to enhance the user experience, improve security, and fix bugs, rather than introducing major disruptions to core features. The reported issue of the screen flickering and displaying a white screen after an update is likely caused by factors that are not explicitly mentioned in your post.

iOS updates primarily focus on improving system performance, introducing new features, fixing bugs, and enhancing security. They are designed to preserve your personal data, settings, and information intact.

During an iOS update, your device's operating system is upgraded, but your personal data, such as contacts, photos, messages, and other information, should remain unchanged. However, it's always a good practice to perform a backup of your device before any major update to ensure that your data is safely stored.

It's important to note that while an iOS update itself should not alter personal details, it's possible that certain features or settings may be adjusted or improved with the update. In such cases, you may need to review and adjust specific settings to match your preferences after the update.

Always make sure to read and understand the update details provided by Apple before proceeding with an iOS update, and follow best practices such as backing up your device to minimize any potential risks or complications.

If the issues you mentioned are indeed caused by iOS, it's likely that numerous users who have upgraded to iOS 16.6 are experiencing similar problems. However, in order for the community on this forum to provide helpful responses, it would be beneficial for you to specify the nature of the issue you are encountering. Without this information, it may be difficult for others to address your concern effectively.