There are a few reasons why this could occur:
1. The Coordinator of that site has deactivated you.
Your coordinator could have done this because you no longer work for the organisation. In this case remember your username and password. If you begin work for another organisation that uses PeopleSafe your PeopleSafe ID number can connect you into the site quickly and easily.
If you still work for the organisation get in contact with your PeopleSafe Coordinator. They'll be able to help you out.
2. You've been playing and have selected 'No' when showing the organisation in your dropdown.
Quick fix. Click on the connect notification icon - find out where that is here. Scroll down and find the organisation and click on the 'no' in the 'Show In My Dropdown' field. It will change to yes and you will have access again. Refresh your browser and you'll be ready to go.