A couple of small adjustments to Killian's code, but which may not be necessary. This will ignore any files without a Doc extension and check for multiple instances of the search string.
Regards
MD
[VBA]
Sub Main()

Const TARGET_FOLDER_PATH As String = "C:\TEMP\"

Dim fso As FileSystemObject
Dim oTargetFolder As Folder
Dim f As File

Dim appWD As Word.Application
Dim docSource As Word.Document
Dim oSearchRange As Word.Range

Dim rngPartnumber As Range
Dim Rw As Long, Paras As Long, Chk As Long


Set fso = New FileSystemObject
Set oTargetFolder = fso.GetFolder(TARGET_FOLDER_PATH)

Set appWD = New Word.Application
For Each rngPartnumber In Range("partnumbers")
Rw = rngPartnumber.Row
For Each f In oTargetFolder.Files
If UCase(Right(f.Name, 3)) = "DOC" Then
Set docSource = appWD.Documents.Open(TARGET_FOLDER_PATH & f.Name)
Set oSearchRange = docSource.Content
With oSearchRange.Find
.ClearFormatting
.MatchWholeWord = True
.Text = rngPartnumber.Text
Do
If .Execute Then
docSource.Range(docSource.Paragraphs(1).Range.Start, _
oSearchRange.End).Select
Paras = appWD.ActiveWindow.Selection.Paragraphs.Count
Cells(Rw, 256).End(xlToLeft).Offset(0, 1).Value = f.Name & " Page: " & _
appWD.ActiveWindow.Selection.Information(wdActiveEndPageNumber) _
& " Para: " & Paras
End If
If Paras = Chk Then Exit Do
Chk = Paras
Loop
End With
docSource.Close False
End If
Next f
Next rngPartnumber
appWD.Quit False
End Sub
[/VBA]