I am trying to create a formula that will sum up the values of a cell on
multiple lines.

i.e. The product name "Twix" appears on multiple lines in a worksheet, to
the right of the cell is a value that varies. I want a formula that looks
for all references of the word "Twix" in a worksheet and then sums up the
vales that correspond to the reference. There by giving me a total number
for all amounts of "Twix" on the worksheet.

I have been trying this now for 2 weeks and it is doing my head in! Please
help.