In some scenarios, the F7 key does not switch between code and designer and back anymore.

The only thing it does is switch from designer to code.

This seems to be related to some profilesettings.

To fix this, you can do the following:

• Go to Tools – Options – Environment – Keyboard (Extras – Optionen – Umgebung – Tastatur)
• Set focus in „Press Shortcut Keys“ text box („Tastenkombination drücken“)
• Press F7 or some other keystroke you want
• The „Shortcut currently used by“ („Tastenkombination wird momentan verwendet von“) box will show the command currently invoked by the keystroke.
• Set focus to „Show Commands Containing“ („Befehle mit folgendem Inhalt anzeigen“) and type ToggleDesigner („AnsichtDesigner“)
• This will select the View.ToggleDesigner („Ansicht.AnsichtDesigner“) command in the list box of commands
• Next press the „Assign“ („Zuweisen“) button to assign the keystroke shortcut to the command. Note: if you select „Global“ it might replace one of the other mappings of F7. I selected „Text-Editor“ to get it working.
• Click „OK“ to the options dialog

Thats it! Now you can switch back and forth again.