Below is a function that I use as a module that makes an API call to open a file. Here is in example on how you would use it. I am going to Assume the the button is on the same form as a text box to display the file path and name. then your code would look like this
Me.TextBox_Name = ap_FileOpen()
use this code below in a module
Option Compare Database
Option Explicit
Private Declare Function ap_GetOpenFileName Lib "comdlg32.dll" Alias _
"GetOpenFileNameA" (pOpenfilename As OPENFILENAME) As Long
Private Type OPENFILENAME
lStructSize As Long
hwndOwner As Long
hInstance As Long
lpstrFilter As String
lpstrCustomFilter As String
nMaxCustFilter As Long
nFilterIndex As Long
lpstrFile As String
nMaxFile As Long
lpstrFileTitle As String
nMaxFileTitle As Long
lpstrInitialDir As String
lpstrTitle As String
flags As Long
nFileOffset As Integer
nFileExtension As Integer
lpstrDefExt As String
lCustData As Long
lpfnHook As Long
lpTemplateName As String
End Type
Public Function ap_FileOpen(Optional strTitle As String = "Open File", _
Optional strFileName As String = "", _
Optional strFilter As String = ""

As String
Dim OpenFile As OPENFILENAME
Dim lngReturn As Long
If Len(strFileName) = 0 Then
strFileName = String(255, 0)
End If
'Note: if you are looking for certain files put the extension of that file where you see the .txt and change Text Files to The appropriate file type Name
If Len(strFilter) = 0 Then
strFilter = "Text Files (*.txt)" & Chr(0) & _
"*.txt" & Chr(0)
End If
OpenFile.lStructSize = Len(OpenFile)
OpenFile.lpstrFilter = strFilter
OpenFile.nFilterIndex = 1
OpenFile.lpstrFile = strFileName + _
Space(255 - Len(strFileName))
OpenFile.nMaxFile = 255
OpenFile.lpstrFileTitle = strFileName
OpenFile.nMaxFileTitle = OpenFile.nMaxFile
OpenFile.lpstrInitialDir = CurrentProject.Path
OpenFile.lpstrTitle = strTitle
OpenFile.flags = 0
ap_GetOpenFileName OpenFile
ap_FileOpen = Left(OpenFile.lpstrFile, _
InStr(OpenFile.lpstrFile, Chr$(0)) - 1)
End Function