It looks like a bug to me but you could try using the copy settings wizard. To do this set up the SW interface as you want it then click on the Solidworks Resources Icon on the top right hand side of the screen (house icon circled in picture below) to get the task plane to fly out. Then select the "Copy settings wizard" this will run a program that will allow you to save all your SW settings and shortcuts.
Then close SW and reopen it. If everything is missing again use this wizard to restore your settings. If you have to restore your settings every time you start SW then there is a bug. You could go to your control panel, then programs and features. select solidworks from the list of programs and then select "change" (beside uninstall) from the top of the list this will bring up the SW installer from where you will be able to select to repair SW.
If none of these work you should contact your VAR.