For example to reset the default view camera to the origin with rotation=0, scale = 1 etc:
ALT G – resets position to (0,0,0) origin (Grab)
ALT R – resets rotation to 0, 0,0 (Rotation)
ALT S – resets scale to 1,1,1 (Scale)
ALT T – resets Tilt to 0,0,0
To reset the cursor:
SHIFT-C= CentreZero View. The 3DCursor is set to zero (0,0,0) and the view is changed so that all Objects, including the 3Dcursor, can be displayed.