The main dash page should be blank in the absence of a search term:

(Unless your settings are set to record file and application usage) as shown below and you've not recently cleared your usage data:

By the same token you can turn off online results in the dash by matching this setting:

If adjusting these settings as desired doesn't provide the desired results you may need to reset your unity configuration.
Edit: Based on your newest comments I believe that you may have recently cleared your usage data. As long as your settings are set to record file and application usage it should eventually repopulate with your recently used files and applications provided you have them selected in the filters.
To the best of my knowledge the recently used stuff that shows up in the dash is accessed from ~/.local/share/recently-used.xbel if you've inadvertently deleted this file your history is lost.