If the Ribbon bar has disappeared,
Type into the command line "Ribbon".
Hit "Enter".
This will bring back the Ribbon bar.
To remove the ribbon bar, Type "Ribbon", and select RIBBONCLOSE.
This will remove the ribbon.
If the Tabs bar have lost some of its tabs, such as Block, Annotate, Help, etc.
Right click in the tabs bar This will bring up the context menu.
Select "Show Tabs" to expand the selection. This will provide a list of all the possible tabs that can be shown.
Select the ones you want displayed and deselect the ones you don't.