If he/she was temporarily ill, he/she would simply not work on that day. If the present were to be permanently ill to a state where they are unable to serve or if they were to die, the vice president would then step in.
The Vice President would take over in His place.
congress
I the president dies, the vice president will take his/her place. I don't know for how long, though.
If the president cannot perform his duties for any reason the Vice President assumes the Presidency. If the Vice President cannot perform the Speaker of the House assumes the duties of the President
the vice president
You would elect a new vp but if it were the president the vp would take his place.
If the House Speaker would become president due to the sudden deaths of both the president and vice president, he would nominate a new vice president who after confirmation by Congress would take his place if he died. If he were to die before a new vice-president was confirmed, the new Speaker of the House would take his place.
Next would be the Vice-President, and then the Speaker of the House if something where to happen to the Vice President.
the government would probably do an early election
In a case where both the president and vice president fail to complete a term as president, the Speaker of the House would take their place. This has not yet happened in the history of the United States.
Congress sets the president's salary. To prevent congress from usingthis power to influence the president, a salary change cannot take place untilthe beginning of the next presidential term.
In this event , the new president would be sworn in and become president. If the outgoing just keeled over, he would be put on a stretcher and carried away to a safe place. If he was shot, all would run for cover and there would be a delay in the swearing in, but it would take place .