Regarding absence in an interview due to unavoidable situation

I attended the interview of CGI on 16th July, 2016. I got selected and was asked to come for the next two technical rounds later. I was unable to attend the interview on that day due to an unavoidable situation. Is it possible for me to attend the CGI interview atleast again from the first round? Please help me in this.

yes u can apply again.

How? Whenever I hit apply button. It is telling me already applied.