This is RELATED to my map making, but its a problem with photoshop cs...so I figured this would be as close as i could get to the right place to post.

Ive been working on a map for a while now, its all coming out very nicely, but all of a sudden, something changed. In my picture itself, under the layer view window, it says index right next to the thumbnail. I cant use brushes, i can only make a selection, cut it, copy, it, move it, or use the pencil tool, and fill in selections with the paint bucket tool. I REALLY need brushes for my map making, and i dont know why the layer is suddenly locked, anyone have any idea how i can fix this? my map is only about 25% done and will stay that way until i can get the brushes to work on it again. Hmmm...thanks for any input