The PBM_SETRANGE message sets the minimum and maximum values for a progress bar and redraws the bar to reflect the new range.
PBM_SETRANGE wParam = 0; lParam = MAKELPARAM(nMinRange, nMaxRange);
Returns the previous range values if successful, or zero otherwise. The low-order word specifies the previous minimum value, and the high-order word specifies the previous maximum value.