search for a text file in the sytem and search for the string in the text file

i want to search for a text file called 'data.txt' in the system...and search for a string called 'hello world' in the file...the below code retrieves the first path of the file.. from this path i have to get the text file and search for the string

Private Declare Function GetLogicalDriveStrings Lib "kernel32" Alias "GetLogicalDriveStringsA" (ByVal nBufferLength As Long, ByVal lpBuffer As String) As Long
Private Declare Function SearchTreeForFile Lib "imagehlp" (ByVal RootPath As String, ByVal InputPathName As String, ByVal OutputPathBuffer As String) As Long

Public Function SearchAllDrives(pstrFile As String) As String
Dim i As Long
Dim strDrives() As String
Dim strMatch As String

For i = 1 To EnumerateDrives(strDrives)
strMatch = SearchDriveForFile(pstrFile, strDrives(i))
If Len(strMatch) <> 0 Then
SearchAllDrives = strMatch
Exit Function
End If
Next
End Function

' Populate a 1-base array with drive designations
' for all drive types. Return number of drives found.
Public Function EnumerateDrives(pstrDrives() As String) As Long
Dim i As Long
Dim strBuffer As String
Dim strDrive As String

ReDim pstrDrives(1 To 1)
strBuffer = Space$(255)
strBuffer = Left$(strBuffer, GetLogicalDriveStrings(255, ByVal strBuffer))
Do While InStr(strBuffer, "\")
strDrive = Left$(strBuffer, InStr(strBuffer, "\") - 1)
i = i + 1
ReDim Preserve pstrDrives(1 To i)
pstrDrives(i) = strDrive
strBuffer = Mid$(strBuffer, Len(strDrive) + 3)
Loop
If pstrDrives(1) = "" Then
Erase pstrDrives
EnumerateDrives = 0
Else
EnumerateDrives = i
End If
End Function

Public Function SearchDriveForFile(pstrFile As String, Optional ByVal pstrDrive As String = "C:") As String
Const MAX_PATH = 260
Dim strPath As String
Dim lngReturn As Long

strPath = String(MAX_PATH, 0)
pstrDrive = Left$(pstrDrive, 1) & ":\"
If SearchTreeForFile(pstrDrive, pstrFile, strPath) <> 0 Then SearchDriveForFile = Left$(strPath, InStr(1, strPath, Chr$(0)) - 1)
End Function