If your web statistics stopped rendering new stats recently there could be a problem with how the server is recording access logs or history files. Before opening a support ticket you can try uninstalling then reinstalling your web statistics from the web interface. You can do so without losing your access logs or history files.
If you still cannot view your web statistics for the last few days then open a support ticket explaining in detail what the problem is with your statistics including the last known date that your statistics were functioning.