are you sure It's installed?
try the following commands:
/home/manny> rpm -qa | grep -i mplayer
mplayer-codecs-win32-qt-6.0-2
mplayer-common-0.91-1
mplayer-codecs-win32-qtextras-1.0-2
mplayer-codecs-linux-real-9.0-2
mplayer-font-iso1-1.0-1
mplayer-codecs-linux-xanim-1.0-2
mplayer-0.91-1
/home/manny> whereis mplayer
mplayer: /usr/bin/mplayer /etc/mplayer /usr/share/mplayer /usr/share/man/man1/mplayer.1.gz
command line to install rpm:
[root@mybox rpms]# rpm -Uvh mplayer-common-0.91-1.i386.rpm
Preparing... ########################################### [100%]
package mplayer-common-0.91-1 is already installed
[root@miles rpms]#
If you need to get the rpms again, you might want to try
http://rpm.pbone.net/
under SEARCH, you can limit all rpms to RH9....
hope this helps,
manny