Language change doesn't work in ubuntu 15.04

Recently I've installed Ubuntu 15.04, everything had worked fine, but suddenly language change stopped working. I don't know what could be the cause of this, because I didn't notice it right away. Now, I've tried to assign different shortcuts to language change, I've tried to use language icon in the top right corner and simple reboot of course. Nothing seems to work. Could you please tell me what could be wrong and what can I do with it?

UPD: forgot to mention that in the top menu my second language(Russian) is present and I even can choose it, but when I type it's still English. UPD2: I've tried to add another language and even change order of input sources, but it didn't work out either. My input language is always English.

1.I recommended you to read this Ubuntu documentation about "use alternative input source" .

It is explaining it step by step .

2.you can try reconfigure the keyboard configuration with this command

dpkg-reconfigure keyboard-configuration 

I hope it helps you.

My problem was that the shortcut for change kept setting to "Shift L" or such. I couldn't get rid of the <Mod2>.

After trying dconf, gsettings, gconftool, gconftool-2 and other, I found out in other question that I have to turn off NumLock and set the shortcut again.

See https://bugs.launchpad.net/ubuntu/+source/unity/+bug/981628