You could use the TRANSPOSE function.

If your worksheet contains

a1 = 1
b1 = 2
c1 = 3
d1 = 4

then enter '=TRANSPOSE(A1:D1)'

into cell E1, but instead of pressing Enter, press Ctrl+SHift+Enter to
make it an array formula. This will put curly braces around the
formula, and E1:E4 will equal A1:D1.