E-mail disappeared

[#1]

Hi,
Yesterday, I had a problem with an e-mail sent to me which hasn`t happened before. (the problem,I mean:) )
I`m using the new Webmail through Plusnet and when I double clicked  on it, it disapeared and opened up the next below mail whick had already been opened previously.
Have searched  in the other folders deleted,draft etc. but it insn`t there.
Any ideas how to find it?
Regards
EL

[#2]

Do you use a normal email client on one of your computers (or phone) to collect mail using POP3? If so that message could have been downloaded to your computer and deleted from the server.
IMAP/Webmail might still have the link to the message but there would be nothing at its destination - giving the behaviour you described.

[#3]

There's a possibility you've been hit by a known but extremely elusive bug which can result in messages disapearing into the ether. 
It's probably not much help,  but more information can be found here..  https://community.plus.net/forum/index.php/topic,105430.0.html

[#4]

You cross referenced a problem I was having. I think I've resolved that one by setting the inbox to display by received date rather than sent date.
I don't think I've had messages completely disappear as appears to have happened in this case.