Good afternoon susanjayhawkfan,
Welcome to the Apple Support Communities!
I understand you are not able to import last year's tax return from H&R block. You may need to contact H&R for help populating the information from their server to this year's tax return. If you saved your documents last year as a PDF file you may be able to find them on your computer or use Time Machine to restore the document. Hopefully you have a printed document as well to refer to.
Narrow your search results on Mac - macOS User Guide
Restore items backed up with Time Machine on Mac - macOS User Guide
Take care.