My hp 5510 photosmart printer will not print in black

Make sure you have run a cleaning cycle before spending money replacing anything. Sometimes the print heads will get a little dry and a color or multiple colors will stop printing. Have you replaced the black cartridge recently? Make sure you have pulled all the tape off correctly. There is an air hole that needs to be opened usually under the tape that will prevent the ink from flowing out of the cartridge. Let us know what your results are after checking the cartridge and running a cleaning.