Did you have color in your face prior to your laser treatments? If yes, there is a chance dermarolling will re-pigment your skin. The cells that produce the skin pigment melanin reside about 0.3 mm deep in the skin. A 0.5 mm roller (roll twice or three times a week) is the best for lost pigmentation.
However, the problem in your case is that if your entire face is depigmented, no melanocytes will migrate from normally pigmented skin into the depigmented patches. Normally, when you roll or needle a depigmented patch of skin and a little outside of its borders, the melanocytes from the surrounding normal skin migrate into the needled/rolled area.
Dermarolling can also in some cases "wake up" melanocytes in the skin, respectively make the skin function as it should, including pigment production.
Furthermore, when you are lucky, some melanocytes from normally pigmented skin will get stuck to the needles and be introduced to the depigmented areas by rolling.
If there is normally pigmented skin somewhere on your face, roll over it when you are rolling your face.
If you whole face has no pigment, first try to trigger melanocytes by simply rolling your face. If you get no results in six months, attempt melanocytes transfer from other parts of your body to your face.
Select skin that is very well pigmented somewhere on your body, and roll over it several times with a 0.5 mm roller, then immediately roll on your face, then again on the pigmented skin and again on the face etc.
One important thing: Melanocytes only produce Melanin upon sun exposure. If you want to re-pigment you face, you must expose it repeatedly to the sun after dermarolling – not immediately after but several days after. You do not have to bake yourself for hours.
Nevertheless, some sun exposure is absolutely necessary.