5000 item limit- worked before and after changes not working anymore

Hi, I think I know what I did wrong. I assumed that if I did the "append to" query in Access whereby I push the rows from the updated version of the excel table to the sharepoint list that the item codes which are unique fields would cause those existing records in the SP list to update. Instead it created those lines as new lines increasing the total number of records. I ran this query numerous times as i kept getting errors on the query but it appears that those queries were at least partially successful. The original number of items was 2540 and now it's 10x that amount. Is there a way to retrace my steps and restore my list to an earlier version before all these new items were added?