The term "laminate flooring" usually refers to flooring boards made of fiberboard with a plastic surface layer that is stamped and decorated to look like wood. You can't make dramatic changes to the appearance of laminate flooring because you can't sand off the finish. If you want to darken the colour of laminate flooring, you may have some success with a wood stain -- but since you can't remove the laminate's original appearance, you can't change a dark colour to a lighter one. Moreover, since the stain won't penetrate, you'll have to cover it with a protective finish if you don't want it to rub off.
Mix floor cleaning detergent with hot water in a bucket and use it to mop the floor. If the floor has a coat of wax, use a detergent that will dissolve and remove it. Let the floor dry for several hours.
Fit a floor buffer with a 120-grit sanding screen and run the buffer over the floor. This is called "screening," and it will knock down the finish of the laminate without wearing through, making the flooring surface porous enough to accept a stain. Vacuum the dust when you are finished, and wipe the floor with a damp rag or tack cloth.
Start at the corner farthest from the door and spread stain, along the grain of the wood pattern, with a rag or paintbrush. Wipe it away with a second rag, going with the grain again, before it has a chance to dry. You'll be able to spread the stain more evenly if you divide the floor into sections. Spread stain on a section and wipe it off before moving on to the next section. Let the stain dry overnight.
Spread one coat of clear finish on the floor with a finish applicator. Working from the wall furthest from the door and moving toward the door, spread a line of finish on the floor and drag the applicator through it in a continuous movement from one end wall to the other. Overlap half the width of the applicator on each pass. Let the finish dry and cure for 24 hours before walking on the floor.
If your final finish coat is grainy or otherwise unsatisfactory, screen the floor with a 120-grit screen and spread another coat. If you don't want to rent a floor buffer, sand the floor lightly by hand or with a sanding pole, going with the grain and using 120-grit sandpaper.
If the stain dries on the floor before you have a chance to wipe it off, it will create a blotch that will detract from the floor's appearance.