Windows don't find the arduino. NEED HELP!

Hey guys,
I've a problem with my arduino mega:
Today I could upload programms and so on, everything worked fine. But now the arduino is not even detected by windows.
I checked the cable, tried an other one. Tried other computers - but it didn't help.
The power light is on, when I press the reset button or connect reset to ground the "L"-led is blinking.
The last thing I did with the arduino was testing an IR-sensor by Sharp.

Has anyone ever experienced this? Is there a way to solve the problem or is the arduino damaged?

edit: tried the loopback-test ( http://arduino.cc/forum/index.php/topic,73748.0.html ) , I'm failing at number 5. Windows does not recognize the board!

Has anyone ever experienced this? Is there a way to solve the problem or is the arduino damaged?

If everything was working, then you did some electrical things with the board, then it does not work, then the board could be damaged. Have you tried rebooting the computer? If you shorted something on the board, you may have tripped the USB fuse on your computer.Rebooting usually resets the fuse (although leds on the board burning do indicate power).

HI,
I'm not a newbee in computer related things. i rebootet the computer twice and lookued up in the device manager if there are any crashed usb ports - there arn't.
ther is also n arduino. thats the reason why i'm writing here!

... I tried to connect the board with an old usb-cable to the board (tx, rx, and grd), and the not working usb cable as power supply. nothing happened.
is there an other way to connect the arduino with a computer. for example with a serial interface (yes my laptop supports a serial interface), or a paralell port?

please help me. i need the ardunino working tomorrow!!!

ther is also n arduino. thats the reason why i'm writing here!

I have no idea what that is saying. :roll_eyes:

sorry for my bad english.
I forgott some letters. That should mean: in the device manager there is no arduino.

If there are no changes in the device manager no matter if the board is plugged in or not, then either the USB converter chip has serious amnesia - or much simpler: it is dead.

The fact that the L-LED is still blinking shows that the main microcontroller is still alive - to some degree at least. You might still use the board if you get yourself a proven-to-work USB/serial adapter and connect that to the serial pins that go to the dead chip. Ideally you'd replace the dead chip, but that requires SMD soldering skills.

If you did anything with the 3.3v pin on the board, then a short on this pin could have killed the USB serial chip if it is a FTDI chip.