Can laxative abuse or overuse of laxative cause ringing in the ears?

Very unlikely: Ringing that is perceived as arising in the ear in the absence of an external source of sound is called tinnitus. The most modern theory for its origin is that it is caused by spontaneous firing of electrical stimuli from the inner portion of the temporal lobe of the brain (the highest center for hearing). It is highly unlikely that the abuse of laxatives would be the cause of tinnitus.