if you mean that before your scroll wheel was stiffer with much more pronounced "clicks" and now it scrolls more freely like it did not have any clicks then it could be that you can fix it.
if you took apart your mouse, the scrollwheel switch will look similar to this. there is a plastic disk with grooves (teeth) that rotates around and a metal piece with a raised bump which the plastic disk rides against. the metal piece riding in and out of the bumps on the plastic disk are what generates the feel of "clicking" and also generates resistance.
it is possible to use two small screwdrivers to bend this metal piece closer to the disk or to make the bump a bit more pronounced which will change the feel of the scrollwheel (it might take a few tries to get it right). its also possible to replace the switch (they arent that expensive)