Hi Mandar,
I restarted the listener
SQL> select sde.st_point(0,0,0) from dual;
select sde.st_point(0,0,0) from dual
*
ERROR in line 1:
.ORA-28595: Extproc-agent: invalid DLL-path
ORA-06512: in "SDE.ST_GEOMETRY_SHAPELIB_PKG", line 12
ORA-06512: in "SDE.ST_POINT", line 176
I'm not running the ArcSDE application server.
I checked I had the Microsoft Visual C++ 2008 SP1 Redistributable Package (x64) installed, but nevertheless re-installed it. The installer offered to repair my existing installation, so it was definitely installed previously.
I've included a screenshot to show you the version of the C++ Runtimes installed on my machine.