If the Sun were to suddenly gain enough mass to significantly alter its gravitational pull on Earth, the consequences would be catastrophic. However, the exact outcome would depend on various factors, such as the amount of mass gained and the distance between Earth and the Sun at the time of this event. To provide a general answer, I'll assume a scenario where the Sun's mass increases dramatically and it starts pulling the Earth toward it.
If the Sun were to gain sufficient mass to overpower Earth's orbital velocity, the Earth's trajectory would be altered. Instead of maintaining its current orbit, the Earth would begin to fall toward the Sun. The time it would take for the Earth to reach the Sun's surface would depend on the specifics of the scenario, including the increased mass of the Sun and the distance between the Sun and the Earth when the event occurs.
However, it's important to note that such a scenario is highly unlikely to occur in reality. The Sun is a massive object, and any sudden increase in its mass would require an extraordinary event, such as the collision and merging of two or more stars. This is not something that we expect to happen in the foreseeable future.
In summary, if the Sun were to gain enough mass to alter Earth's orbit, the Earth would fall toward the Sun and the time it would take to reach the Sun's surface would depend on the specific conditions of the scenario.