C: drive says its full but no files?

I have a 71.4 GB C Drive, 36 programs installed and it says I only have 10.4 GB left - how is that possible? I have small iphone vidos/pictures - why would it be so full? I had a computer crash a few years ago - i'm sure everything is still there somewhere.

Your operating system takes around 35-40 gb, so that doesn't leave very much for programs(about 20gb from what you are saying)

Download treesize
http://www.jam-software.com/freeware/

this will show you what is taking up the space