The ImageList collection items also can take a key for easy look-up:
imageListLarge.Images.Add(files, Bitmap.FromFile(files)))
Then you can reference them by the key:
Dim bmp As Bitmap = imageListLarge.Images("my file name")
When you add your ListView item, you can use the ImageKey as the reference:
Dim item1 As New ListViewItem("2J-F108-100", "2J-F108-100")
this assumes you added the image with the same key:
imageListLarge.Images.Add("2J-F108-100", Bitmap.FromFile(...)))
Also, make sure to add your images before adding the ListItems:
Dim imageListLarge As New ImageList()
imageListLarge.ImageSize = New Size(100, 100)
Dim filesList As String() = Directory.GetFiles(filePath & "Resources\IETMS\")
Dim files2 As String
For Each files As String In filesList
files2 = files.Replace(files.Substring(0, files.LastIndexOf("\") + 1), "")
files2 = files2.Replace(".ico", "")
imageListLarge.Images.Add(files2, Bitmap.FromFile(files))
Next
ListView1.LargeImageList = imageListLarge
ListView1.View = View.LargeIcon
Dim dirs As String() = Directory.GetDirectories(filePath & "Resources\IETMS\")
For Each dir As String In dirs
dir = dir.Replace(dir.Substring(0, dir.LastIndexOf("\") + 1), "")
ListView1.Items.Add(New ListViewItem(dir, dir))
Next