where did all my emails go?

[#1]

I use a secondary email account for leisure purposes. I access it via Plusnet webmail.
It has suddenly lost all messages - incoming, trash, sent, junk etc.
Is there any way of recovering them?
I'm having no probs with my normal emails which I access with Outlook 2010.
Thanks.
Al

[#2]

They came back this p.m. but now they've gone again javascript:void(0);