As a Google apps administrator, you have the ability to restore any user accounts that have been manually suspended by you or another administrator or that have been automatically suspended by Gmail for being "at risk" or for exceeding account limits. Once an account is restored, users can once again sign in and access all of their services and data.
This article will teach you how to restore suspended Gmail accounts. Please note that this article strictly applies to Google administrators.
Restore Accounts as Gmail Admin
Head to the Google Admin console and click Users.
Under Filters (at the side of the user list), choose Suspended users. If you don't see the filters automatically, you can access them by clicking the Filters button.
Click the suspended user's name to access their account page. Once on the account page, click Settings > Restore.
Note that in order to see the Restore user option, you must be signed in with an account that has the Suspend Users privilege enabled, such as a Super Admin or User Management Admin. You can also restore users in bulk using the Admin SDK.