Dim my_file As Worksheet
Set my_file = Workbooks.Open(Filename:=ThisWorkbook.Path & "\important file" & Date & ".xlsx").Sheets(1)
'do anything
Workbooks("important file" & Date & ".xlsx").Close SaveChanges:=False
Like
:Dim my_file As Worksheet, file_name As String
file_name = "important file _some_symbols_ .xlsx"
If file_name Like "important file*.xlsx" Or file_name Like "important file*.xls" Then
Set my_file = Workbooks.Open(Filename:=ThisWorkbook.Path & file_name).Sheets(1)
'do anything
Workbooks(file_name).Close SaveChanges:=False
End IF