The last update vanished photos from my iphone

Or they were on there I guess.

With none of the normal safety precautions like a backup you should not have let it update.

Are you sure Photos should not be turned on in Settings, your name, iCloud?

In Photos app on the phone look in Recently Deleted, and in Library tab.

Also check by signing into iCloud.com in Safari and see if the Photos tab has them.

Is everything else on the phone?

It depends on how you manage your photos.

• iCloud Photos
• iCloud backup
• Computer sync and backup
• Third party app like Google
• Just on the phone

If the last option then you cannot but that would be very unusual to lose them in that case.

Come back with detsils.