Problem with Mail

[Clive Read]

I've recently converted to ADSL Broadband (in Spain) a nightmare all of 
its own.

Without warning tonight my iBook with OS X 10.6.2 rebuilt itself to a 
clear desktop, then showed all my icons. Not sure what happened next, 
and in what order, but I was faced with a message asking whether I 
wanted to Import messages from another eMail client and, as I do not 
have any other, I said no.

Everything seemed OK until I tried to send an eMail and all of my eMail 
preferences (names passports, pop and smtp data for five ISP's has gone 
- not the end of the world) but so have folders  and loads of eMails

Any bright ideas as to if (what) I can do to recover them?

Clive in Spain