Why is my tool part dimmed out and unusable.

[Brookswood]

When I post or edit a message of mine, the tool bar has suddenly become dimmed out. I can’t underline, use italics, or setup a quote. My guess is I accidentally changed a setting, but I sure don’t know where to find it and set it back to normal.

 

[John cycling]

You've apparently clicked the BB code box [ ] in the upper right corner, i.e. to the left of Preview.
Click the BB code box [ ] again and those other functions will become accessible again.