New message system - old messages gone

I was recently upgraded to the new message system on Facebook. A lot of my old messages have disappeared. Is there any way to get my old messages back? When I say a lot have disappeared, I mean like 90% of my old messages are gone. I never delete any messages.

Hello,

What 'new message system' do you mean? Can you kindly provide a screenshot?

Where all the conversations are grouped into one message. So instead of having 100 separate messages with different subjects, all my conversations with each person are grouped into one conversation per person. There is no subject.

Apologies for the extra long delay; your reply must have gotten lost in my emails. Sorry about that.

This is part of Facebook's new message system. However, old correspondents from each contact should still be available if you scroll all the way up.