It didn't disappear immediately; was able to send a couple messages earlier today. But since this afternoon, I cannot find the app anywhere on my iPhone 5s. If I go into my contacts and send a message to someone through there, it works and I can see the previous messages back and forth with that particular person. But the app iself is just gone.
Hi webdoyenne,
Welcome to the Apple Support Communities!
I understand that you are unable to locate your Messages application on your iPhone. There may be a couple of different steps I would recommend in this situation.
First, I suggest searching for Messages with Spotlight as described in the attached article below. If the application is able to be found, please look on all pages of applications and in folders to locate the application.
Search with Spotlight - Apple Support
If you are still unable to locate Messages, you may want to consider resetting your Home Screen Layout. To complete this task, please use the attached iOS 8 User Guide (page 28) as a reference.
https://manuals.info.apple.com/MANUALS/1000/MA1565/en_US/iphone_user_guide.pdf
Start over. Go to Settings > General > Reset, then tap Reset Home Screen Layout to return the Home screen and apps to their original layout. Folders are removed and the original wallpaper is restored.
Best regards,
Joe
Yeah, this is what I ended up doing...and then had the joy of reorganizing all my apps again. <sigh>
iMessage app disappeared after iOS 8.3 upgrade
