If you've lost access that you had before, here are some things to check:
- Software updates could cause tabs to have been moved.
- If you are an employee, you can check with your "Administrator" if he has made any changes to the access profiles or the subscription of the center.
- If you are the administrator, perhaps you have made changes to the chosen modules. You can check in the administration, under "Billing".
- If you have late payments, your subscription may have been temporarily suspended. In this case, you will have been warned in advance.