Have you tried printing a test page? My friend recently replaced the black cartridge in her HP printer bur her documents were all printing in purple. I printed a test page and realised no black ink was getting through.
I put some lukewarm water in a dish, put the part of the black cartridge in the water until ink began to come out into the water.
A gentle wipe with a tissue to dry it then back into the printer and it worked. The new cartridge was just needing a 'kick start'.
Yours may be a different problem but it is worth trying.