Postgresql schema "public" does not exist

Question

When I was working on postgresql database, I delete some users using command

=>set role "test-admin" ;
SET
=> drop owned by "test-admin" cascade;
DROP OWNED.   
=> drop user "test-temp";
DROP ROLE

but when I do

\dn
List of schemas
 Name | Owner
------+-------
(0 rows)

The public schema does not exist anymore. I can still see a bunch of users when run \du, I can also see names of database when do \l.

The error I saw is: "Error: could not find schema 'public' while looking for owner".

Looks like public schema was either dropped or not accessible. I did not drop schema explicitly.

My questions are:

• why does public schema disappear?
• will drop owner of schema public also drop public schema?
• how can I bring it back?
• Should I manually recreate it?
• Since I can still see databases, how can I associate the database with public schema again?

I tried all the approaches I can think of (such as login as users with different privileges), the public schema is still no available.

Thanks for the help in advance.