Private Sub Buscar_Click()
Dim archivo As String

Open "C:\mi-carpeta\" & txtA & ".txt" For Binary As #1
archivo = Space(LOF(1))
Get #1, , archivo
Close #1

txtSalida.text = archivo
End Sub

Private Sub guardar_Click()

Open "C:\mi-carpeta\" & txtA & ".txt" For Output As #1
Print #1, txtA.text
Print #1, txtB.text
Print #1, txtC.text
Close #1

End Sub

A-4254
A-57456
H-9

Private Declare Function SendMessage Lib "user32" Alias "SendMessageA" (ByVal hwnd As Long, ByVal wMsg As Long, ByVal wParam As Long, lParam As Any) As Long
Const EM_GETLINE = &HC4

Private Sub Command1_Click()

Dim Respuesta As Long
Dim Texto As String

Texto = Space$(10)
Respuesta = SendMessage(Text1.hwnd, EM_GETLINE, 1, ByVal Texto)

MsgBox Texto

End Sub