Suden pics disappearance

Are you using iCloud photos? If so, then it may have been an issue with your iCloud sync. You can check to ensure your photos are still in iCloud by logging into www.icloud.com with a browser on the computer to check and see. You should not worry about losing photos as long as they are in iCloud.

Did you go and check to see if they were there as I suggested? What were you doing with your iPad when this occurred? Pictures do not just disappear and then reappear on their own. If you are concerned about the photos, then take the time to import them to your computer for safe keeping. See this, Transfer photos and videos from your iPhone, iPad, or iPod touch - Apple Support

If your photos are not saved in iCloud, they should be saved in your backup, however I would also use the Transfer link that I gave you before to ensure they are backed up to a computer. I would say not to update until you have straightened out the photo issue.

I'm sorry, but I'm a user here, not an Apple employee. We volunteer here, and do not share contact information here. If you post a question, then you will receive responses from me, or anyone else that reads your question.

See this, If your computer doesn't recognize your iPhone, iPad, or iPod - Apple Support

You're welcome. And to be honest, at this time, there seems to be a widespread issue with iOS updates at the Apple Server level, so I would hold off on that for right now until that gets resolved.

Not a problem. Have a nice day.