after I select delete message on handheld and mailbox. Also on my yahoo account, how can I access my different folders? Thanks.

I think after BIS 2.0, there is no more online mail account that you can check with your desktop. It's soley delivered to your BB. You might be out of luck with deleted messages.

you cannot undelete emails
however the emails you delete from your handheld from your Yhoo! account will be in th trash folder - and still accessable via computer