DELL OPTIPLEX GX240 PC RESTORE

I have been trying to restore this computer back to the
original settings, but the does not bring up a
Symantac window. So I will assume this computer is older
than 7/2004. I don’t have the ResourceCD either. Is there any
other way to restore this computer?

http://support.dell.com/support/edocs/systems/opgx240/