I have had this happen to me once, in my case it was some bug messing up with the UI profiles. Unfortunately it was only fixed by upgrading SolidWorks. You can customize the existing toolbar by right clicking the label of the tab and then clicking on "Customize CommandManager".
At this screen you can drag button shortcuts onto your tools, what you're looking for is "Commands>Flow Simulation Main>Wizard"
A word of warning, if you do customize this new toolbar then the default Flow Sim toolbar may be hidden when you do your next upgrade, you'll have to go into the customize menu again and reveal the new bar with the default button layout.
I plugged in my Desktop monitor with my laptop to work in an extended setup, that might have messed up the UI Profiles!!
I have already pulled some options from the customize menu, but its Sooo tiny. I have to adjust with the situation then!!