Does touching things that have been touched by an impurity, such as a washbasin touched by someone who cleaned himself with his hand, invalidate ablution, and is it necessary to sprinkle water on it before ablution to avoid that?

The default status of things is purity unless their impurity is certain. Therefore, there is no need to wash a sink merely due to a doubt about its impurity. Touching an impurity does not invalidate ablution (Wudu'), and the person performing ablution removes it without redoing Wudu'. As for the presence of impurity on a limb before ablution, there is a difference of opinion among scholars, and the preponderant view has been clarified.