leandro, if this happened without any damage or any other cause I'd proceed like this. Check the dock connector and make sure that all the pins are straight, clean it of any debris or corrosion. Try a new USB cord as well as a different USB port. Do not use a USB hub and use a USB port that comes of the mother board. On a Desktop, it is usually the back USB ports. Try a hard reset. To reset your iPod Touch, press and hold down the Sleep/Wake button and the Home button at the same time for at minimum of ten seconds, the LCD should clear and the Apple logo appear. Once the Apple logo appears you have done a reset. Should none of that work, I would start disassembling the ipod as shown here and replace the battery. Again check all cables for corrosion and debris and that they are properly seated. If that fails, I would consider changing the dock connector. I hope that this will get you started and that you get your iPod functioning soon. Good Luck.