It's likely that your bathroom sink is made of ceramic or porcelain. Most stainless-steel or stone sinks are in the kitchen. One poor characteristic of both porcelain and ceramic is that they can chip or crack easily if heavy objects are dropped or banged into them. Fortunately, if your bathroom sink is chipped or cracked, the supplies you need to make the repairs yourself are readily available.
Rinse the sink with warm water, and gently scrub the damaged area with a soft-bristled brush to remove build-up and loose pieces of ceramic from inside the crack. Dry it with the soft cloth.
Fill the crack with the epoxy adhesive. Use one of the paintbrushes to apply several layers of epoxy until the crack or hole has been filled. Remove excess epoxy surrounding the repair with the point of the toothpick and a damp sponge.
Paint over the repair with a matching colour appliance paint. Use a fresh paintbrush or the paint applicator underneath the lid of the paint bottle. Allow the paint to dry for 24 hours before using the sink again.