What diagnosis for fever for 17 day without any symptoms.crp -ve, esr 22&56 .wbcs 3500, neutrophl 1000, lymphocytosis.ldh 468 no thrombocytopenia?

Asked and answered: You have a fever of undetermined origin (FUO). The lab data you provided is not sufficient to warrant even a guess as to what may be going on. You need to see a doctor and have this fully evaluated, and the longer you try doing this on your own the worse it may get. Good luck.

Mono?: Obviously, you are in a workup by someone. Keep going. Mononucleosis has some of these characteristics, though "no symptoms" would be improbable given the blood results. The old addage: "common diseases occur commonly, rare diseases occur rarely" advocates that mono might be a good bet. But, that's only a statistical perspective.