So I got my arduino uno r3 couple days ago and it worked fine for the first day the second day I connected a 12v to the 5v pin in the arduino by mistake,
now it is blinking the orange led which was controlled by a code to blink once every 1 second which is the last code uploaded and the green one is starting on, it flashes 3 times when connected to the pc at the beginning but the pc can't see it nor in the device manager or the ide , I trieed same cable with another uno and it worked,
Any ideas?
I heared I can controll it via the serial ports 0, 1 tx rx, but what will I need?, I have a bluetooth sensor can I use it? but i guess this needs me to upload a sketch first to read data from the sensor?
How can I fix this issue or get a workaround to upload my sketches if the usb port is not working?
The usb is powering it but not reading the arduino in the pc.
Then the USB chip (next to USB port) is dead. You feeding 12V to 5V may have damaged all of the ICs on board but for some reason the mcu (large rectangular IC) is still working (you don't know how much of it has been damaged). You don't have the skills or tools to replace and reprogram that USB IC that is apparently dead so may as well move on and remember the lesson you learned, always power off your board before wiring stuff and check wiring twice before powering anything on. If you pry out the MCU and keep it for a future stand-alone project, please label it a suspect of damage so years from now you won't be scratching your head why this MCU isn't working as it should.
You can buy a so-called FTDI adapter like the ones people use to program the SparkFun ProMini; those do bring out the DTR pin as well which is needed to reset the 328P.
But I agree with @liuzengqiang that you more than likely have damaged more and components that are now still working might eventually die.