Hello , my name isXXXXX have 13 years of hands-on repair with computers. I will be happy to try assisting you with this problem to the best of my ability.
Do you have your Mac with you at the moment?
In your library (current user->library) open the Preferences directory.In there you will find a file named:com.apple.dashboard.plist Drag this on to your desktop then Reboot and see if that makes any changes to start off with.Usually at this process that file will go back to it's original behaviour so there will be no harm done to either the computer or files.Please let me know once you have tried this, so we can continue with the next steps.
I've tried this but there is no com.apple.dashboard.plist in the preferences directory.
found it! working - thanks.