Can not update my dsc on mca21 portal

Hello Experts, I'm trying to update my DSC on MCA21 Portal. While I'm going through instructions I selected my DSC by clicking "Select Certificate" Button then system shows the message "You are already registered as director/designated partner/authorised representative against the userid: My UserName. Please answer the hint question below, if you want to update your DSC". But I don't remember the answer. In this case what should I do to update my DSC? It is very very urgent for our company that our one of two director want to resign and my DSC is required to proceed further. Thanks, Mahesh Jarange