I'm unhappy with my PhD
As @Buffy says, you should probably talk to someone about your situation in general. A PhD is hard under optimal conditions, let alone when coping with loss and depression. There’s no need for you to suffer alone.
As for your research progress, nobody here can give you a right answer. You should talk with your advisor whose job is to resolve such issues. They may suggest switching fields, techniques or collaborators; they may give you a different problem you like better; they can tell you that you should quit the program and do something else. This is all very dependent on you, your advisor and your institution’s attitude towards grad students.
If your advisor is not someone you can discuss this with, you have a bigger problem on your hands. Talk to an ombudsperson, senior mentor, student counseling services, vice dean for graduate matters or any other resource your school offers. You may get a different advisor, switch to a masters or a plan will be worked out with your existing advisor.
Good luck!