hi @kostya129, do you mind sharing with us the exact model number of your g75? (g75vw/x-yyyy); i'm sorry i couldn't make assumptions of your OS even if i crawled your posts.
are you running stock windows? w7 or w8? from your previous posts, you have messed with the sound quite a bit. what did you do?
Try going to the control panel/notification area icons. If the box to set behaviors for the volume control is greyed out, you have a known issue with no confirmed fix. some times a restore will solve it, some report a registry fix, sometimes removing the driver in safe mode will work. The last time I dealt with it, it was an evil little bug I picked up in a download. try this and see what happens, it's the reg fix from MS. http://support.microsoft.com/kb/945011#FixItForMe