@stuti Pandey I understand that you are unable to sign up for Azure free account. You also tried with different email address, and it failed.
It usually happens if you had used the same information (Email, phone number, credit card details) before to sign up for Azure free trial account.
Azure Free Trial FAQ - https://azure.microsoft.com/en-in/free/free-account-faq
If you have not used Azure free trial account before, you may contact Azure billing and subscription management support by raising a support request. The ticket enables you to work closely with the support engineers and get a quick resolution to your issue.
Here is the link - https://docs.microsoft.com/en-us/azure/azure-portal/supportability/how-to-create-azure-support-request to create support case.
FYI: Azure Billing and Subscription Management support is included in the Basic Support Plan without any charge.
https://azure.microsoft.com/en-us/support/plans/
Hope this helps!