So a couple times it's happened to me that when I was using Photoshop or Illustrator in Mac OSX, I couldn't access the hand tool with the spacebar.

So after a quick Google search and having to close down my half a dozen browser windows, I learned that if are unable to access the Hand Tool with the spacebar keyboard shortcut in Adobe Photoshop or Adobe Illustrator, try restarting Firefox, Chrome, or whatever browser you are using and it should be back to normal.

Why your browser conflicts with keyboard shortcuts in Adobe Photoshop is beyond me. But thankfully all it takes is a quick restart of your browser to get it back to normal most of the time.