Given a year and week number, below formula finds the Sunday as the date.
=MAX(DATE(F2,1,1),DATE(F2,1,1)-WEEKDAY(DATE(F2,1,1),1)+1+(G2-1)*7)
Where F2 has the year and G2 has the week number.
For week 1, this would always give 1-Jan as the date.
Given a year and week number, below formula finds the Sunday as the date.
=MAX(DATE(F2,1,1),DATE(F2,1,1)-WEEKDAY(DATE(F2,1,1),1)+1+(G2-1)*7)
Where F2 has the year and G2 has the week number.
For week 1, this would always give 1-Jan as the date.