All notes on iPad disappeared after software update

Your issue is known - affecting many.

Apple have provided a support page for this specific issue:

If you don't see your iCloud notes in the Notes app - Apple Support

There are also a number of third-party articles that describe the problem and resolution. Here is one from OSXDaily:

https://osxdaily.com/2024/11/18/fix-missing-icloud-notes-iphone-ipad/

Another from 9to5mac:

https://9to5mac.com/2024/11/07/iphone-notes-gone-deleted-apple-notes-app-heres-the-fix/

Do you have a backup? You might want to search for your notes there

I want all my apps and games updated on my iPad please