Do you want to find those emails back?You can try a 3rd part data-
recover tool called Advanced Outlook Repair. It can help to undelete
the emails you delete by mistake. You can download a free demo version
at http://www.datanumen.com/aor/aor.exe .
Are you holding Shift when you press delete?
For lost pst file items: There is a powerful tool to recover deleted emails,
contacts, calendars, notes, and more from PSTs. The software uses advanced
deleted e-mail recovery methods to recover Deleted Items from PSTs. http://www.recover-deleted-email.net/