Further to my issue.
I restored my website to a previous date, and diagnosed that it is an issue with recent update of ACF plugin ver 6.12.
I dont know how to avoid updating this plugin in future as well.
Thanks @topi for your response
As matter of fact I do not use any fields or fields group in ACF plugin itself. I have been creating forms with Frontend Admin for ACF plugin, and there is no option/requirement to register fields with PHP.
However the issue appeared once I was testing with group fields in ACF. I temporarily made a test group filed and deleted that.
After this I realized that all my existing forms made through Frontend Admin for ACF plugin has been disappeared and now even unable to add more fields in new forms as well.
Tried to uninstall/install ACF and Frontend Admin plugins, but the issue is still there.
Can still help, please?
