You can't password-mask an InputBox in Access. What you would need is to create a new form, as a Dialogue Box with at least two controls: a textbox with a password input mask, and a command button to allow the form to open.
For example, let's say your main for that you want to protect is named Form1:
Create a form named frmPassword with a textbox control named txtPassword and with the Input Mask property set to Password, and a Command button named cmdOK. Set the form's Popup and Modal properties to Yes.
In the Code Module for frmPassword, enter the following code:
Private Sub cmdOK()
If PWD = "password" Then
Me.Visible = False
In the Code Module for Form1, enter the following code:
Private Sub Form_Open(Cancel As Integer)
DoCmd.OpenForm "frmPassword", , , , , acDialog
If SysCmd(acSysCmdGetObjectState, acForm, "frmPassword") Then
If Forms("frmPassword").CurrentView Then
DoCmd.Close acForm, "frmPassword"
Cancel = True
What I did in my form was simply go to Form / DesignView, select the Password field and then to that fields properties. There I set the InputMask to Password and that is all it took. Didn't take any coding of any type. Just giving my take on this.