Missing Tabs? / Show Tabs, Toolbar
Click on the View Menu item. In the popup window - make sure both Show Tabs and Show Toolbar items have checkmarks. If not, click to add checkmark. - click on Tabs to show. - in the popup click to put a checkmark on any item that does not already have a checkmark and is not greyed out. You may have to repeatedly click Tabs to show until all items are selected.
For easy access to certain functions like Write and Print checks, Reconcile, etc. customize the Quicken Toolbar. To do so, right-click on a blank spot in the Toolbar line and click Customize Toolbar (or click View / Customize Toolbar). In the Customize Toolbar window be sure to put a checkmark at "Show all toolbar choices" and then proceed with adding the icons you want on the Toolbar.
Pre-Q 2017 only: While you're in there, also put a checkmark at "Show global search".