Not able to connect to Blynk server from command line using "blyn-ser .bat"

I am new to Blynk so I watched a Youtube video and following the steps I was trying to connect to blynk service from the command prompt. But after some time connection is not established and it is displaying the following message.

Are you using Windows?

Which sketch are you using?

yes ,I m using windows 10 and the sketch is Arduino_Serial_USB

Are you using the Arduino Serial sketch unaltered and have you obtained your authorisation code and included it in the sketch?

Your Arduino is on COM 7 right and you don’t have the port open in the Arduino IDE or any other utility?

yeah my port is COM7 and it is not being used by any other utility.Only I have pasted the authorization code in the sketch otherwise no alteration are being made by my side in the sketch

Hello. Please follow step-by-step comments in USB sketch.

ya I have tried these steps given in that sketch bt it still shows the error at command promt.