Since you imply you need blank rows so you can autofill them (I assume from data in row above), one way of adding in blank rows is:
(1) in first cell of a column not presently being used, type the number 1 and then select this cell and rest of column (all current rows in worksheet).
(2) go to edit - fill - series; change step value to 2; click ok
(3) you should now see 1, 3, 5, etc. in this column.
(4) in cell in first row beyond all current rows, type the number 2 and then select this cell and the same number of cells in this column to match the rows numbered 1, 3, 5, etc.
(5) repeat step 2; these rows will be numbered 2, 4, 6, etc.
(6) now sort your worksheet by this column
(7) delete this column