For the past 2-3 weeks I have had no sound ingame and I don't know why.
let me list what I've done in attempts to fix it.

-Reinstall the game. While doing so I had trouble installing Adobe air so I had to redownload the Installer, delete the .FSS file manually, reinstalled,, rebooted and the game worked but still no sound

- Went to update my sound drivers but it told me drivers were up to date.

-I use mumble ingame which is a voice chat like vent. I've used it for a while even when I had sound before. Just one day the sound stopped working in-game. No settings were changed and no 3rd party software was added.

-I have also searched these forums for help but couldn't find anything of use

So I have done all of the above and I still have no sound ingame, or at the login screen. If you want I can post or email my Logs and turn my .FSS document to a .txt document and email it to an admin/or upload to this post here.

P.S. downloading the newest version of adobe air or updating adobe air outside of the launcher cause the launcher to malfunction and crash. That's what I found while reinstalling.

bump: found out i dont have no sound but the sounds very very very low and barely audible

bump still need help doees riot have at least 1 person that knows what's going on?

wow you guys don't even have the common decency to try to help or at least tell me you don't know what's wrong.... pathetic

another ****ing bump

ive had the same issue recently after using teamspeak, I cant figure out how to turn it back up and even setting in game sound to max makes it barely audible with headphones, but once out of game the menu sounds and clicking are super loud.. im not sure how to fix this, ive uninstalled, restarted pc, reinstalled restarted pc, and ran it as admin, still nothing that I can find to fix it

actually I figured out the program and how to fix it, first if you are running windows 7, its easy. go down to the speaker icon, click it, and you should see the word Mixer, open the mixer, make sure you have league of legends running amd be in game for the correct sound to show, youll see 2 league of legends, one at low settings the other at high, turn the lower one up all the way and there you go, fixed, as for XP users and mac, im sorry I haven't messed with either yet but im sure the same applies... hope this helps

Thanks Akroma that helped me out ive had the same problem and it fixed it. Thanks over and over