I am trying to install webMethods workflow server v 4.6 , it installed successfully. But if I would like to start server from windows----> services, there is no workflow service in the services list. Please let me know what I have to do.

SVS.
Have a look at the readme.txt file for Workflow in the WorkflowServer root directory. Section 3.2 says:

3.2 Problems Installing Workflow Server as a service

1-5HQDK
Workflow Server occasionally fails to install as a service on
Windows 2000, when the Windows Services Control Manager Window is
open. If you are reinstalling or upgrading Workflow you must
first stop the Workflow Server service and then exit the Services
Control Manager. Alternatively, you may may add the service as
follows:

• Close the Services Control Manager.

• From an MS-DOS command prompt, go to the directory that
  contains the Workflow Server installation.

• Type this command as one line where INSTALL_DIRECTORY is the
  directory in which Workflow was installed:“WorkflowSvc.exe -i
  -Djava.class.path INSTALL_DIRECTORY\SrvcWorkflow.jar wrkdir=
  INSTALL_DIRECTORY”.

• If you need to remove the service, run the command
  “WorkflowSvc.exe -r”

Regards,

Wayne