I am using arduino mega 2560 R3 board.It was working well,Bt nw it is not recognized by my both laptop and desktop.How ever the installed code is working well.Only I can't do is upload a new code.what should I do? :confused: :confused: :confused:
1)Try a new USB cable 2) Inspect the USB connector on the mega board- you may have a bad solder connection ... use a 10x or higher magnifier as hairline cracks can be the problem
3)maybe try this starting with the paragraph "The current bootloader in the Arduino mega board..." I have an older board, and this does work showing that the firmware is likely not totally corrupted.
4) Other option is to attempt to replace the bootloader. Nick Gammon's webpages have great hints.
I've had the same issue with my UNO, along with excessive heat coming rom the USB chip. It could be that your board is damaged.