Fear not, friend! This is extremely common and something that Alteryx does on purpose.
When you installed a new version (or reinstalled an old one), Alteryx set you up on a default view. That means they've hidden tools and entire menus from view. To get them back, you need to get to the 'Configure Tool Palette' menu. It looks like the screenshot in "Alteryx - Configure Tool Palette" below.
In most modern versions of Alteryx, you get there by clicking the + in the top-right corner of the canvas, as shown in "Alteryx - Add or Remove Tools" below.
In older versions, you may have to find that window in User Settings.
After that, either click the check boxes next to the tools you want or select 'All' under the Preset menu at the top to have everything show up (see "Alteryx - Add All Tools" below).
Did this work for you? Do you have any follow-up questions? Let me know at https://analytics.orasi.com/contact/.