Hi CHSpen44
welcome to the Appole (user-to-user) Community!
Re: "Using Live Captions : Today live captions has disappeared. What did I do wrong?"
Am no expert in this area, yet your question certainly deserves some response.
Could have been any one of several possible reasons, and you may not have done anything "wrong"..
Live Captions could be "hidden" at the moment because there is no audio.
It is easy to accidentally press a keyboard shortcut.
Eg: If you customized Live Captions, you may have set up a keyboard-shortcut or such, to turn it on or off.
Maybe Live Captions is turned off in Settings (eg: after an iOS update installed updated apps.)
See: Settings > Accessibility > Live Captions, where you can turn Live Captions on or off.
If you haven't already you may want to update your iOS to the newest version:
(NB:It is always wise to back up your iPhone data securely before updating.)
About iOS 18 Updates - Apple Support says iOS 18.1.1 is the latest.
Eg: says: "This update provides important security fixes and is recommended for all users".
Else, if already using iOS 18.1.1:
You could try restarting your iPhone: (Deletes temporary files, re-establishes connections, may update recent setting changes, and often restores order if something is not working as expected.)
________
If needed: See if tips in iOS 18 version of "Get live captions of spoken audio on iPhone - Apple Support" may help.
or
You may want to contact Apple's Accessibility Support Team for assitance with Live Captions:
See: How to contact Apple for accessibility support - Apple Support
All the best :-)