You can query Dynamic performance view (v$parameter) to know your database is using PFILE or SPFILE.
SQL> select value from V$parameter where name= ‘SPFILE’;
A non-null value indicates the database is using SPFILE.
A null value indicates database is using PFILE.
You can force a database to use a PFILE by issuing a startup command as
SQL> startup PFILE = ‘full path of Pfile location’;