I added Raster data from a folder into ArcMap 10.1 and I cannot seem to drag any layer within the Table of Contents.
Can someone help?
On the Table of Contents pane just below the words "Table of Contents" there should be 5 buttons.
Ensure that you are on the first button called "List by Drawing Order".
This mode allows you to do the dragging that you want.
A trap for new users is that adding a table to ArcMap changes the Table of Contents to List By Source View (because that is the only View Type that lists tables), which they often do not notice, causing them to "lose" the ability to re-order layers.