You can create either one of these reports by running the Special Donor Export/Listing Report (located under Reports > Gifts > Donor Reports > Special Donor -  Export/Listing).  

This report was designed for reporting and/or mailing to donors based on their prior giving history.   After the report appears on the screen, you may elect to export data, which includes address & salutation, for mailing to the donors.

The initial screen allows selection on gift dates and total amounts given between the selected dates.   It also allows you to exclude people if they've recently given.

To create a LYBUNT report, put the date range you want to include (e.g. last year) in the Include donors who made a gift from and through fields.   Then put the first day of this year in the Exclude donors who made a gift since box.   The result will show you all donors who gave last year but not this year.

To create a SYBUNT report, just expand the initial date range in the Include donors who made a gift from and through fields to include all years you want to consider.

After clicking OK, you can make further selection on Fund and other criteria.

For more information on running this report, go to FIMS Help Online > Index > Donor Reports > Special Donor Export / Listing .