LYBUNT (pronounced "lie-bunt") means donors who have given Last Year But Unfortunately Not This. This refers specifically to donors who gave in the immediately preceding (last) calendar/fiscal year but not in the current calendar/fiscal year.
You can create a filter under CRM for your LYBUNT report. Please go to CRM and find a column named "Last Year Received Amount" on the Grid. Please click on the 3 small dots to the right on the column and choose filter is "not empty". Please find a column named "YTD Received Amount" and right click on the 3 dots on the right and choose filter "is empty".
You can save this LYBUNT filter by adding it to the Filter Name over to the far left side of the screen and then hitting save.
Once you are satisfied with the results you can go under Actions and export all the data to Excel, you can send this group a text message, create an email list and/or prepare a mailing all right from the grid.