Currently Being ModeratedFeb 3, 2014 6:50 AM (in response to Sam J Sly)
(you need to hold the "Option" key when clicking "Go" from the Finder menu to access the [user]/Library folder)
You can delete one or all widgets from there.
Also go to [user]/Library/Preferences and trash the com.apple.dashboard.plist and com.apple.dashboard.client.plist files.
Empty the trash and when you relaunch Dashboard it should function as if it were the first time you opened it.
Currently Being ModeratedFeb 3, 2014 7:56 AM (in response to Sam J Sly)
Open the Activity Monitor
Click the Process Name heading to sort alphabetically
EVERY item that says Dashboard... click it and click the octagonal icon at the top left to terminate the process, Close the Activity Monitor and THEN empty the trash.
Reboot, and Dashboard will work like new.