The first time I launched Dreamweaver CS5 I didn't like the default code / design view my files appeared in. So I choose a preference setting where files appear in a single pane in code view. Unfortunately I don't remember where this setting is located. I'm not sure if this is the culprit but I somehow lost the ability to toggle Split, Design, Live Code, Live View, and Inspect on any web file (.html, .htm, .asp, etc.). Could someone help me figure out how to enable these modes?
Edit > Preferences > File Types / Editors
The "Open in code view" field is poorly labelled and trips many people up.
It should say "Open only in code view"
Remove .html, .htm, .asp, etc. from the list
Thank you! That was it!
I am having the same problem, except the solution suggested by John Waller isn't working for me.
I opened a .css file and was prompted by a suggestion above the code/design windows stating "Inspect mode is most useful with certain workspace settings." and I clicked the "Switch now" option to which I was trapped in a code only mode without the option to edit anything other than css!