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Try to boot Ubuntu from dvd/flash. If sound codec will not work, then it may be a hardware failure; otherwise (after rebooting to Windows) uninstall all Realtek software from Programs and features, reboot, system should install generic sound drivers itself. If they work, try to reinstall Realtek drivers.
Edit: After listening and analyzing your sound sample, I suspect some parasitic signal penetrating into your sound subsystem - there are two primary frequencies: 266Hz and 4533Hz (multiplier is 17). Please check that your input jack connector isn't dirty or damaged, preferably using analog headset. Also check and clean inside of your laptop if possible.
Furthermore, Realtek codec driver has three sliders in microphone settings: Recording volume, Playback volume and Microphone boost (translated). The last is hidden under button. Make sure they are not set to Maximum.
Last edited by valihrach; 27 Nov 2016 at 07:01.