Hope you are doing great.
change directory to root drive "C:\", and type the command below into an admin cmd prompt window,
c:\mongodb\bin\mongod.exe --config c:\mongodb\mongod.cfg --install
then type net start MongoDB after which you will get the message "The Mongo DB service was started successfully"
Then go to the control panel Start>Administrative Tools>Services, scroll to Mongo DB in the list of services and change start up type to automatic, if you so desire. Press ok.
Now type c:\mongodb\bin\mongo.exe and you should be connected to the Mongo test DB.
Please try and let us know if you have any other issue so we can help you out.