iphone no longer puts full stop when double tapping space bar

Settings, General, Keyboard, toggle on "." Shortcut

You got help from volunteer users not from Apple.

Put any suggestions here:

Feedback to Apple

With a feature request

Product Feedback - Apple

Would have been preferable to simply have "double tap for period"-n"shortcut".

My sense is that the multitude and variety of options in the settings now are complicating things and putting it beyond what lots of ordinary people can/want to use.

Keep it simple so we don't have to look for help from Apple for things that most people want and things that should be apparent..

Thanks.

Welcome, glad it was solved