Installing SAP Host Agent Manually...

 Download the Latest SAP Host agent from SAP Software Center

• https://launchpad.support.sap.com/#/softwarecenter
• SUPPORT PACKAGES & PATCHES
• By Alphabetical Index (A-Z)
• H
• SAP HOST AGENT

Select the Host agent version & download the OS depended Installation file 

Store the Downloaded file to a temporary directory (Example \tmp)

Uncar the downloaded host agent SAR file to the \tmp directory using below command

spacar -xvf HOST_AGENT_FILENAME.SAR

After successfully uncar the file, Install the host agent using below command,

saphostexec -install

Host agent will install now,Enter the password of the administrator user

After Installation got completed, check the version.

UNIX   - /usr/sap/hostctrl/exe

Windows  -  %ProgramFiles%\SAP\hostctrl\exe

saphostexec -version 

Check the host agent status

saphostexec -status