Hi, put this in your main module.
Sub Start()
ClearAll
UserForm.Show
Unload UserForm
End Sub
Sub ClearAll()
Application.ScreenUpdating = False
ClearWorkSheet
ClearActiveWindow
ClearApplicationControls
Application.ScreenUpdating = True
End Sub
Sub ResetAll()
Application.ScreenUpdating = False
ResetWorkSheet
ResetActiveWindow
ResetApplicationControls
Application.ScreenUpdating = True
End Sub
Sub ClearWorkSheet()
With ActiveWindow
.DisplayGridlines = False
.DisplayHeadings = False
.WindowState = xlMaximized
' xlMaximized or xlNormal
End With
'ActiveSheet.SetBackgroundPicture ("C:\My Documents\My Pictures\Yosemite.jpg"

'Just an example to show how to set a picture on the background, otherwise it will just be white.
End Sub
Sub ResetWorkSheet()
With ActiveWindow
.DisplayGridlines = True
.DisplayHeadings = True
.WindowState = xlMaximized
' xlMaximized or xlNormal
End With
'ActiveSheet.SetBackgroundPicture (""

'Disables the background picture when reset
End Sub
Sub ClearActiveWindow()
With ActiveWindow
.DisplayHorizontalScrollBar = False
.DisplayVerticalScrollBar = False
.DisplayWorkbookTabs = False
End With
' Application.DisplayScrollBars = False
' Turns scrollbars off for all workbooks
End Sub
Sub ResetActiveWindow()
' Resets the scrollbars for all workbooks
With ActiveWindow
.DisplayHorizontalScrollBar = True
.DisplayVerticalScrollBar = True
.DisplayWorkbookTabs = True
End With
End Sub
Sub ClearApplicationControls()
Dim OneBar As CommandBar
' First the normal screen
With Application
.DisplayFullScreen = False
.DisplayFormulaBar = False
.DisplayStatusBar = False
End With
' Hide all Command Bars
On Error Resume Next
For Each OneBar In CommandBars
OneBar.Visible = False
Next
On Error GoTo 0
' Now viewing full screen
With Application
.DisplayFullScreen = True
.DisplayFormulaBar = False
.DisplayStatusBar = False
End With
' Hide all Command Bars
On Error Resume Next
For Each OneBar In CommandBars
OneBar.Visible = False
Next
On Error GoTo 0
' Disable the Menu Bar only required once
CommandBars("Worksheet Menu Bar"

.Enabled = False
End Sub
Sub ResetApplicationControls()
' First viewing full screen
With Application
.DisplayFullScreen = True
.DisplayFormulaBar = True
.DisplayStatusBar = True
End With
' Turn on main CommandBars
CommandBars("Standard"

.Visible = True
CommandBars("Formatting"

.Visible = True
' Now the normal screen
With Application
.DisplayFullScreen = False
.DisplayFormulaBar = True
.DisplayStatusBar = True
End With
' Turn on main CommandBars
CommandBars("Standard"

.Visible = True
CommandBars("Formatting"

.Visible = True
' Re-enable the Menu Bar
CommandBars("Worksheet Menu Bar"

.Enabled = True
End Sub
And in the button that exits the UserForm and goes back to Excel...
Private Sub BtnExit_Click()
'Runs procedures that reset Excel toolbars and exit the interface.
' Also saves the workbook and exits Excel completely.
Me.Hide
ResetAll
'ThisWorkbook.Save
'Application.Quit
End Sub
Okay, couple of things to note down here. In BtnExit_Click, ThisWorkbook.Save and Application.Quit are commented out. Uncommenting them will close Excel and save the workbook.
Also, you will need to disable the QueryClose (the little X in the top right corner). Use the following code in the code for the form that has the Exit button above in it...
Private Sub UserForm_QueryClose(Cancel As Integer, CloseMode As Integer)
If Cancel <> 1 Then
Cancel = 1
End If
End Sub
It won't make the button disappear, but will disable it. This is very important, because if someone opens the form, Excel is cleared, but if they don't press the Exit button to exit, then Excel remains cleared. Only pressing Exit button will reses Excel.
I am assuming that Sub_Start() is the procedure that is assigned to your button in Excel that runs the form.
Comment out ClearAll in Sub_Start() and Excel won't clear. Useful for testing.