Uninstalling and reinstalling the program doesn’t touch the file that stores the locations of the toolbars. The ALT+SpaceBar thing is for the various windows if they are loose on the screen; Model Info, Preferences, etc.; not the toolbars.
Since you’ve tried other things and they didn’t work for you, first, close SketchUp. Then go to User/AppData/Local/SketchUp/SketchUp 2023/SketchUp and rename the file called PrivatePreferences.json to something like OLDPrivatePreferences.json. Then find the installer, probably in your Downloads folder, right click on it. Choose Run as Administrator from the right click menu. If asked, choose Repair. After that, open SketchUp. You should be able to enable the Large Tool Set and have it appear on your screen.
Note that renaming or deleting PrivatePreferences has effect on all of your toolbars so you’ll need to rearrange them but it will reset the location for the Large Tool Set. After you’ve arranged the toolbars work on a model file a little or make a new one and save it to ensure the new PrivatePreferences file gets updated.