Safari is the web browser, and if you asked Google, you either used Safari, or you used another computer (although I guess you could have used another web browser ).
If you want to change your Safari home page, you use Safari -> Preferences -> General -> Home Page
If Safari is no longer on your Dock, you can use Spotlight (Command-Space) and type Safari to find it. Then once it is running, you can Control-Click -> Options -> Keep in Dock.
If you changed things so that clicking on a Link in another app no longer opens a Safari window, you can change that via Safari -> Preferences -> General -> Default web browser.
If I have not hit upon an answer to your question, can you please try to add addition information that may help us understand.