Hello @Muhammad haroon,
welcome to this moderated Azure community forum.
Next to all the options given by @Babafemi Bulugbe , There is an extra reason.
Have you used this email address in the past for a free Azure account already?
You can only have a free azure account once for a certain email address. This should be the same for a creditcard.
If the response helped, do "Accept Answer". If it doesn't work, please let us know the progress. All community members with similar issues will benefit by doing so. Your contribution is highly appreciated.