Fastforward/rewind functions

You would need an audio player with that capability, and it would be done inside the program, not with a keyboard key.

Goldwave, a shareware audio editor, has functions for playback control.  Probably other audio (or media) Apps such as Audacity too.  I use Goldwave in my recording studio.

@Zuva  If your keyboard doesn't have the actual Previous/Next Track media keys, then you can either use keyboard shortcuts that may be supported by the specific application you're using, or you can use an application like AutoHotKey to define key combinations that will trigger those media key commands.