It sounds like your account is being flagged for risky behavior. This could mean that someone else is using your password illegitimately, or it's possible that your organization's risk policies detected another behavior that flagged your account.
If your organization has enabled SSPR, you can go to the Password reset portal and initiate the password reset.
If SSPR is not an option or if your account is still blocked after following these steps, your IT admin will need to unblock your account by remediating the risk. The admin can do this by going to the Azure AD (Entra) portal (https://entra.microsoft.com/) > Protect & secure > Risky activities >Risky users > Select the user account you want to unlock > Dismiss user(s) risk.
If you are the admin of the account, you will need to reach out to Microsoft support to get your problem resolved. You can reach either the global support phone numbers or the Azure Data Protection team: (866-807-5850)