This has happened to me today, of course at the time when I urgently need Photoshop(in my case CS4), and I found the solution. If you Googled this and wound up here searching for the fix to this, chances are the problem will fix itself by the time you are reading this, if not, try the trick below:
If you Photoshop is stuck on the Hand tool, try this:
Edit – > Preferences – > General – > [Reset All Warning Dialogs]
Problem should be solved now!