You can start with this function and modify it to make restrict keys if you like. This function will only allow the user enter the Keys you specify on the keyboard.
Code:
Public Sub Text1_KeyPress(KeyAscii As Integer)
    KeyAscii = fnValiText
(KeyAscii,"ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789",True)

End Sub

Public Function fnValiText(arg_sKeyIn As Integer, arg_strValidateString As String, arg_bEditable As Boolean) As Integer

'Dim member variables
Dim m_strValidateList As String
Dim m_sKeyOut As Integer
    
    If arg_bEditable = True Then
        m_strValidateList = UCase(arg_strValidateString) & Chr(8)
    Else
        m_strValidateList = UCase(arg_strValidateString)
    End If

    If InStr(1, m_strValidateList, UCase(Chr(arg_sKeyIn)), 1) > 0 Then
        m_sKeyOut = arg_sKeyIn
    Else
        m_sKeyOut = 0
    End If
        
    fnValiText = m_sKeyOut

End Function