[Evolution] Help! E-mails disappearing

[Keith Shackleton <k shackleton ncf ca>]

I use Linux Mint 13 Mate version.  I have been using Evolution for about 
a year and really liked it until now.

Last week, all my e-mails disappeared inexplicably, leaving a blank 
page.  The calendar and contacts section are still intact.  When I 
download new e-mails from my ISP, these also disappear. My settings 
delete the e-mails from the ISP mailbox when they are downloaded.

I am not highly skilled at Linux troubleshooting. I have tried to find 
where the messages might be hiding.  I suspect they are retrievable 
somewhere. The documentation indicating where mail files are stored is 
not correct in my case. I have done searches for "mail" and "evolution" 
but they yield so many results; I open each file and find that it's part 
of the Evolution system files.

I followed one procedure in Terminal, to get information on a crash and 
no crash info appeared.

Hoping someone can give me guidance as to how to retrieve my messages 
and prevent the same from happening again.  If I can't be assured that 
my e-mails won't disappear, I will have to abandon Evolution.