I am using a samsung tablet .

it has a hard drive capacity of 51 gig.

it has programs installed of approx 1.5 gig.

most of my stuff is held on a separate hd.

Windows control panel tells me I have i have 12 gig available space on the drive.

I can only account for about 2 gig of other files on the pc through the control panel access to my files of all type.

My question is how can I be missing  30 + gig of space ? what can be filling it and can I delete it somehow?

Tons of reasons.  For example, page file (equal to your amount of ram), Hibernation file (~the same size as your ram), the OS, restore points, etc, etc

There is a good 3rd party tool (free) that can tell you what is using the space called Treesize (from Jam software)

You can also run the disk cleanup wizard to delete temp files, etc.  Be sure to include system files when running the disk cleanup