I wonder if any of you are retired FBI agents? lol

I have been told that everything that has been put into a computer is always in that computer. My nephew shot and killed himself the 27 of October. My sister deleted his email because she didn't have his password and it was his email address that kept coming up when she tried to send out any. So, now, because of the circumstances, her isp gave her his password and NOW she wants to access it!!! She thinks you all are brilliant and can make majic and things appear from outerspace.... is there a way to bring back that lost file you think? I'd appreciate any help you could give me cause she is riding me hard on this one! I think only the FBI can do this one! lol Thanks in advance! MB