I have gnats in my home they have bitten my eyelids and my top and bottom lid are swollen even part of my face what can I do for the itching?

Cold packs - plus. Use cold packs for immediate relief, but you can try oral Benadryl (diphenhydramine) capsules. These bites may become infected. If te swelling increases or becomes painful or gets red, go to your doctor quickly.
See a doctor. If these gnat bites are significant enough to cause facial swelling, i would recommend seeing a doctor. You may have a sensitivity to something in the bite.