Windows mail calender problem

Can some kind soul out there tell me what I need to do to get the notifications working on my windows mail calender working please?

It was fine when I bought the machine but stopped giving me notifications when the machine was about a year old and no matter what I look at, I can't find a way to get it kickstarted.

If I open the calender, I get a notification if it's overdue but that's all I get.

Thanks in advance.