how to check

Hi I would like to know how to check What do I have on D driver. I had about 150GB space. I used it for bask upo file. but until recently I had 200GB free space. now only 10. how could that be? all other folders on this driver is empty :/

not 200 but 20

that including hidden folders?

also i recommend defragging the hard drive this may also be the culprit as several times its jsut displaying an old number or a placeholder until the next defrag.