The answer to 'why is my toilet frozen' is that the water in the toilet's tank or bowl has frozen, usually due to extremely cold temperatures. This can happen when the temperature in the bathroom or surrounding area drops below freezing, causing the water in the toilet to freeze and expand, potentially cracking the porcelain or damaging the internal components.
Common symptoms of a frozen toilet include the water in the tank or bowl not refilling properly, the toilet not flushing correctly, or the toilet making unusual noises. In severe cases, the frozen water can cause the toilet to crack or split. To fix a frozen toilet, you'll need to thaw the frozen water, which may require using a space heater, hot water, or other methods to gradually warm the area around the toilet.