How to Fix a Smudged Nail: 1. First, dip your finger or a q-tip into an acetone-based nail polish remover and smooth it lightly over the smudged area of your nail to create an even surface. 2. Then, either find the same polish color you used or a similar hue and paint back over the smudged area. You want this layer to be thick enough that you can’t see through it, but not so thick that it stands out from your other nails. 3. Finish with a topcoat to smooth everything out.