Board with no serial communication

Hi everybody,

I'm experiencing an issue with a new arduino board (MEGA 2560). I can't upload new scripts to the board since the IDE doesn't recognize serial port when I connect the board. The USB provide power supply to the board, it stills running the last script, but I can't upload new ones. I've tried to connect an older board (same model - MEGA 2560) and it works fine. Do you guys think I have burned the board somehow?

You omitted to mention what is or was connected to what so only guesses as to why it is not working as expected.
Maybe add a schematic of whats connected to where and also the last sketch that worked (post code using code tags ( </> )

Maybe also mention which IDE and the OS etc etc.