It is possible to read the sketch in Arduino and dowload it on a PC memory ?
While it is possible to download the compiled program from the Arduino board, it is not possible to recover your original sketch from that file. You could get the assembly listing from the compiled program, but this will have no resemblance to your sketch. It would be faster to just write your sketch all over again than to convert the assembly back into a standard Arduino sketch.
So if you only want to get the compiled program so you can upload it in an unmodified state to other Arduino boards that use the same configuration as your current board, then this is worth doing and I can provide instructions. But if you need your actual code back then I'm sorry to tell you that this is not the solution.