How to Get data from a date range

I need to be able to get data (Week Totals) from the dates Start - End

I need the 52 week total and then day rate total.

Currently it is a very large sum adding the weekly totals together, but when deleting the not required column, I need to add to the formula (=SUM(I26+O26+U26+AA26+AG26+AM26+AS26+AY26+BE26+BK26+BQ26+BW26+CC26+CI26+CO26+CU26+DA26+DG26+DM26+DS26+DY26+EE26+EK26+EQ26+EW26+FC26+FI26+FO26+FU26+GA26+GG26+GM26+GS26+GY26+HE26+HK26+HQ26+HW26+IC26+II26+IO26+IU26+JA26+JG26+JM26+JS26+JY26+KE26+KK26+KQ26+KW26+LC26)

There must be an easier way to do this.

Thanks in advance.