Since you're not familiar with macros do the following:
1- Hit ALT-F11 to get to the VBE
2- In the VBE hit CTRL-R to view the Project Explorer
3- Find your workbook. It should look like:
4- Click the + sign to open the file. Double-click on the item
named "ThisWorkbook" to open the module sheet.
5- Copy the following macro and paste it in this sheet:
Private Sub Workbook_Open()
.EnableAutoFilter = True
.Protect DrawingObjects:=True, contents:=True, _
Now you can hit ALT-F11 to return to Excel. Select the sheet that has your Autofilter and close the workbook.
When you reopen the workbook the Autofilter sheet will be protected but you will be able to use the Autofilter.