A customer says they get "This account is disabled" when they try to sign in. What does it mean?

Their account is blocked in your admin. This happens when someone clicks Block user on the customer, or sets Status to Inactive.

To let them back in:

1. Go to Customers → Manage Customers and search for them. The list shows Inactive under Status.
2. Open the customer and click Activate user, then confirm.

They can sign in straight away. If they have also forgotten their password, set a new one on the Change Password tab.