Here is a quick glance at the default locations of SPFILE and PFILE in different platforms. For instance, Linux and Windows.
Please note that, for Windows, directory name and filename are case-insensitive.
There's no typos in the above path. The default location of PFILE on Windows truly depends on ORACLE_BASE. As you can see, they're somewhat different on path between SPFILE and PFILE on Windows.
It may be different from version to version.
In some situations, DBA use a PFILE with non-conventional path to startup the database. You need more skills to find the location of PFILE.
Normally, parameter files should stay where they are, but the location of SPFILE can be changed somehow, as long as you know how to do it.