Can I get fired for missing work due to a work-related injury?

I work as a maintenance worker at a small apartment complex. I fell at work and had a screw go into my knee cap. I right away told my boss and went to the doctor. I filed a labor and insurance (L and I) claim at the doctor's office. Now I'm being told by my doctor that I can't work for 4 weeks and maybe longer. I also was told by L and I not to work and to listen to my doctor. My boss however is telling me everything is my fault and that I can't have the time off, that she needs me to work. Can I get fired if I don't go to work? I'm doing what my doctor and L and I told me to do but I'm afraid I will get fired. I filed a harassment case against my boss.