I am using below code to get the updated preferences which are existed in workbench.prefs file.
private String nodeValue = "org.eclipse.ui.commands";
IPreferenceStore store = WorkbenchPlugin.getDefault().getPreferenceStore();
String updatedKeyString = store.getString(nodeValue);
But now I need to get default values for key binding's which are in General-Keys-Keys preference page.
You can get the current key bindings from the binding service:
IBindingService bindingService = PlatformUI.getWorkbench().getAdapter(IBindingService.class);
Binding [] bindings = bindingService.getBindings();