did you try putting it in a bag of rice for 24 hours??
make sure you cover your ports or the rice will get in!! that happened to me!!!
you can also try something called a bheestie bag / thirsty bag
whens the last time you backed it up??
how often do you sync to itunes???
try drying it out and report back
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advice section
the most important thing to back up on an iPhone is pictures and videos you recorded with your camera. photo stream does not keep these forever. unless you pay for the iCloud space and use iCloud stream
it is very important that you back up your pictures and videos that you made with the camera to itunes or iPhoto. or you use iCloud and PAY the storage costs. that is the only thing that you are in serious danger of permanently losing
antyhing SYNC'ED to the iPhone with itunes is not in your back ups.
iCloud will keep your contacts, calendar, email, notes, apps, tv shows, movies, music safe ( as long as tv shows , movies and apps are purchased )
books are wishy washy i heard horror stories
iCloud may back up text messages. ( i forgot )i know for sure itunes backs these up.
an actual back up file is only 7 gigs or so. because most of the stuff we put on an iPhone is either sync'ed to the phone with itunes or it its something we purchased or its something that is stored in iCloud, like your phone book
if you are totally out of luck and you can't get that stuff off the phone , then theres a chance that all your stuff is in iCloud or on itunes already and losing the stuff on your phone isn't such a big deal
i hear horror stories about android. like people losing their phone book to a virus
if you never backed up your phone in your entire life, then at least all your apps and media you bought are safe and can be downloaded again from the app and itunes stores free of charge, and all your iCloud stuff is safe
even stuff that is banned is still in your itunes account waiting for you to download it