getting low disk prob

[siddy123]

I m attending the same prob for my win7, free space was about 20gb and now it is 2gb free memory, after that i had boot scan my pc and then defragmented it and i've get 6gb free space on it, and also vary intresting part is whenever i connect external device, the free space is continuously decreases please guide me on this and ans me asap,,,,,,,

 

[galactigus]

Open the drive hold your mouse over each folder and find which one is using so much space and why it should tell you the amount in the folder if you hover over it or right click the folder and click properties.

 

[siddy123]

thanks for your reply,
I 've checked all the folder properties seprately but but it is showing me only 31gb out of 52gb, also i've checked protected operating sys file's properties too but its not that much.