An Admin user has the ability to reactivate a user’s account.  To reactivate a user’s account, access the Admin Console by clicking on your initials in the right hand corner.

Click on Users tab to access the list of users on your account.

On the Users list, make sure that you have the Inactive filter selected so that inactive users are showing.

Hover over the user you want to reactivate and click on the "clock" icon.

A message will pop up asking you if you want to reactivate this user.  Click on Reactivate to reactivate the user’s account.