@Devendra Swami Greetings!
Based on the information you provided; I understand that you've moved a subscription from one Azure directory to another and are now having trouble accessing it.
In the Azure Portal, ensure you're logged in with the correct Global Administrator account and switch to the target directory where the subscription was moved. You can do this from the directory switcher in the top right corner of the portal.After moving a subscription, you may need to assign yourself roles to access the subscription. Since there are no other users/accounts, you need owner role to access the subscription.
In your case, I would suggest elevating your global admin access to manage all your Azure subscriptions. For guidance, refer to this link - https://learn.microsoft.com/en-us/azure/role-based-access-control/elevate-access-global-admin?tabs=azure-portal
This should help resolve your issue. If problem persists, you can refer to the discussion here - https://learn.microsoft.com/en-us/answers/questions/1455267/global-admin-account-locked-unable-to-access-entra or contact Azure billing and subscription management support for assistance 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/
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