Hi Sushanta,
I have checked your account settings and have noticed that even though you are correctly associated to your Partner ID, you are only set up as a basic user for Support, this is the reason that you cannot raise any support cases.
Please follow these instructions in order to upgrade your basic user account to an enterprise support account. I will contact you privately to send you the Site ID to be used.
Upgrading your account will trigger for an automated case to appear in the Customer Care queue and one of the representatives will grant you access. Once this has happened you will receive another automated email informing you that your access has been granted, as well as requesting you to reactivate your password. The reason for the password reactivation is for security purposes.
If this has answered your question please mark this answer as correct.
Thanks,
Elke