Cron job not running

Hi there. It appears the Cron job on our site has stopped running. This is a major issue as a lot of our users are due for renewals but a lot of them haven't been renewed or even put in expired since the cron job seems to have an issue.

I've accessed the front end as suggest in the other Cron job thread as well as checked all the settings so I'm not sure what else to do.