programmer not responding

hey, i've been using arduino for over a month now.. it had been working perfectly except that suddenly now im unable to upload any code to the arduino nor can i use the serial monitor to get the outputs from the arduino via serial communication . The strange part is that i didnt try doing anything either , it just randomly stopped.. although i do have some code on it which turns on an LED based on motion sensors and that continues to work with no issues , the only problem is that im unable to upload any new code to it nor monitor its serial output. Any help would be appreciated.. Thanks..

Which Arduino board? What operating system? See: for suggestions, which may be relevant even if the board was working previously.

its the arduino UNO.. i tried it on windows and ubuntu but no response...i did read the troubleshooting guide.. im a bit scared to RESET cause there is some code in it that already works i dont want that to go away too ..thanks ..

a small update.. im now somehow able to give input to the arduino via a serial connection..but still not able to get any output from the arduino and not able to upload code to the arduino..Really strange..

im still having the same issue.. any help would be appreciated..thanks :)

What OS are you working in? I just recently had some problems myself with both Vista and 7 where the board would suddenly go unrecognized, refuse to upload properly, etc. Turned out all I needed to do was run the IDE as Administrator, and it works perfectly and hasn't given me trouble since.

i've tried on both ubuntu and windows.. dont think its an OS issue..also cause i have a serial connection with the arduino and im able to input via serial connection but dont get any output from the serial connection..Thanks for the reply BTW