Umm, if you're burning and the attack happened while you were offline the report of the loss SHOULD be in the messages under the reports tab. The only thing that could have forced it down and out of messages is if clanmates sent you over a hundred shipments of resources.
In clan battle reports, the losses are saved at the end so the report should be there as well unless, again, your clan got the crap beat out of themselves after your town was attacked (edit: it saves onslaughts too:P) pushing your report to the locked filing cabinet and lost to an inferno.
Either of these two places of reports will bring up necessary information of who the attacker was but not necessarily any other usable information.
Good luck on your sweet revenge!!
It could also be that you have a lag in messages – if you did not get any message at all.
Have experienced this on an alt:
Last messages(s) does not show. Trapped in queue. One have to get more messages for it to be pushed up. This of course is a constant issue - (as in you are always 1+ message short). Very irritating.
Have heard from clan mates that deleting all messages can resolve the issue. Tried this + cleared cache. For me messages are still in lag.
As for "Reports" you'd have to hit invader, harvest some RSS or something else to get a message in that queue.