suddenly cannot print anything on my hp printer

Same here, I have 2 HP printers en they don't accept prints.

No issues on a Epson printer.

Printing with the standard postcript drivers does work, but duplex printing is then impossible

daftu posted a solution which has worked for me in another thread

ftp://ftp.hp.com/pub/softlib/software12/HP_Quick_Start/osx/Installations/Essentials/hp-printer-essentials-S-5_14_8_4.pkg

HTH