Can you put a ladder to the sun and climb up?

First, you would need a ladder approximately 93 million miles long and able to withstand the massive temperatures the sun creates (the corona is around 1 million degrees, the surface is around 5,000 degrees, and the core is around 15 million degrees Fahrenheit). Even if you had this ladder, the sun has no solid surface against which to prop the ladder, and the Earth's rotation would prevent you from having the legs of the ladder on the ground while still pointing the top of the ladder at the sun. In short, the answer is "No".