Are you working as SAP Basis administration?
If yes, then login to the pc where sap router is installed.
check whether command prompt screen is open or not.
If not then go to command prompt
the go to the directory where sap router is installed.
then type the saprouter start command as bellow.
run this command to find the DN:
sapgenpse get_my_name –v –n Issuer
This command will show a string.
Then run this:
saprouter -r -S 3299 -V 3 -K "<string obtained from top>" 
Pls don't close this command prompt screen after saprouter start.
Thanks
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Pra$anta