i'm not sure if there's a built-in funtionality
in .net to solve your problem. in case there's none, you
can try this one.
Dim dt as new DateTime
(DateTime.Now.Year,1,1)
Dim week_number as Integer = 1 'change
week number
Dim days_in_week as Integer = 7
Dim start_date as String
Dim end_date as String
dt = dt.AddDays(( (week_number-1) *
days_in_week) - 1)
While ((dt.DayOfWeek <> DayOfWeek.Monday))
dt = dt.AddDays(-1)
End While