If the php module isn't in the directory it's supposed to be in, somthing went wrong in the install. If you're compiling from source, make sure you use the option "--with-apxs[=/path]"
If you installed from rpms, uninstall, and then reinstall. Then check your httpd.conf for the correct directives and restart apache.
I highly recommend Troel Arvin's php rpms if you want to go the rpm route. Do a google search for "arvin php rpm."
Hope this helps,
Lacey