Hello Smythster69,
Being able to access your Keynote files from your iPhone is a great feature, so we want to help you track down that missing folder.
Let's start with these steps:
Check to see if it shows on other devices or at the iCloud website.
Restart your iPhone, and check again.
Are you still able to open the Keynote app on your iPhone?
You'll also want to check the Recently Deleted folder.
"When you delete a file from iCloud Drive or On My [device], it goes into your Recently Deleted folder. If you change your mind or accidentally delete a file, you have 30 days to get it back. Go to Locations > Recently Deleted. Select the file that you want to keep and tap Recover. After 30 days, your files are removed from Recently Deleted."
You'll find additional information to help locate and manage your files below.
Let us know if you need further assistance. Have a great day.