What can cause a low wbc (3.9), high red cell dist width (14.8), low neutrophil (1.94), and low lymphocyte (1.35)? Everything else came back normal on my CBC and unfortunately my doctor is unavailable to explain the results. Thank you.

Any symptoms? All laboratory results need to be interpreted in the clinical context and the doctor who ordered the tests is usually in the best position to do that. Talk to the doctor who ordered the tests. Having said that, it may be your normal. African Americans have lower WBC count than what may be considered normal. If you do not have fever or any other symptoms. You can wait to talk to your doctor.
Hematologist. In most cases of benign low white blood cell count(leukopenia), I've found that it has been present for years and that the rest of the complete blood count is essentially within normal limits. Your wbc, at 3900, is borderline low with 4000 being the cutoff. Many physicians don't find the rdw very helpful. Autoimmune disease is one cause of new onset leukopenia. A hematologist can advise you best.
Further inquiry . Most physicians think of iron deficiency when they see a high RDW. There is also a link between iron deficiency and leukopenia (low WBC’s). You’ll have to further discuss with ordering provider but symptoms would be helpful, also to see your Hgb and and MCV even though they were reported as normal. But yes, your numbers could very well be the norm for you.