I have a cut from a swiss knife 4 days ago & i haven't done much to it.the edges don't meet & it has a gap?has slight depth.a little itchy.what to do?

Location? Size?: I assume that the cut is on a finger? As long as the cut does not appear infected (unusual swelling, redness, tenderness), the cut is small and you have no loss of function (movement) or sensation (numbness), then you are probably okay to keep the cut clean with normal washing, apply antibiotic ointment and cover with a band-aid. Change the band-aid daily and clean with 3% peroxide if crusty.

Keep clean: And bandage it daily. Apply antibiotic ointment. It will heal and "fill in.". See your doctor for increasing pain, redness, swelling, etc (signs of infection).