The answer to 'why is my sink frozen' is that your sink's drain pipes have likely become frozen due to cold temperatures. This is a common problem that can occur in the winter, especially in older homes or those with inadequate insulation around the plumbing. When the water in the pipes freezes, it expands and blocks the flow of water, causing the sink to back up or not drain properly.
Some common signs of a frozen sink drain include slow draining water, gurgling sounds coming from the sink, and water pooling around the sink base. In severe cases, the frozen pipe may even burst, leading to water damage.