My volume control button cannot be displayed in the notification area, but realtek hd audio manager has taken its place.

Check in the settings of Realtek HD Audio Manager to see if there is an option to change your audio setting manager. Although, is there any specific reason you don't wish to use the software made for your audio device? Chances are if you try to use it in a way that it was not intended, you will have more problems.

1 Check the sound card, cables, and speakers and other equipment is connected properly; run anti-virus anti-virus software;

2 Right-click "My Computer → Properties → Hardware → Device Manager", open "Sound, video and game controllers" if there are any problems, there does not appear in front of the yellow "?." If so, reinstall the device driver to solve.
3. Have sound but not seen the trumpet , open the "Control Panel → Sound and Video Equipment → volume" in "the volume icon in the taskbar" check mark before the marked.
Good luck!