Use error handling.
Private Sub cmdPreviousRecord_Click()
MvToRec Me, acPrevious
End Sub
Private Sub cmdNextRecord_Click()
MvToRec Me, acNext
End Sub
Sub MvToRec(frm As Form, mv As Access.AcRecord)
On Error Resume Next
DoCmd.GoToRecord , frm.Name, mv
Select Case Err.Number
Case 0 'no error
Case 2105
'if first record reached jump to last and vice versa
Select Case mv
Case acNext: mv = acFirst
Case acPrevious: mv = acLast
End Select
MvToRec frm, mv
Case Else
Debug.Print Err.Number, Err.Description
End Select
End Sub