How to restore "postgres" database?

Ouch! I've loaded my backup while being connected
to the wrong database - to the dafeult "postgres" database.

Is there a way to restore it? I currently have:

postgres=# \l
        List of databases
   Name    |  Owner   | Encoding
-----------+----------+----------
 postgres  | postgres | UTF8
 phpbb      | postgres | UTF8
 template0 | postgres | UTF8
 template1 | postgres | UTF8
(4 rows)

It is difficult to find the solution on the web (bad keywords)

Regards
Alex