i just wanna ask a question about Arduino uno board
my board blinks the L led light and the RX led light at the same time although i did not use the serial communication and when i connect it to the USB in my computer the computer does not read the board
Does it show up in device manager? If it shows as unknown device, have you installed the Arduino IDE using the installer? If you used the .zip package, and have never installed the IDE with the installer, you have to point windows to the driver.
Is the cable known good? There is a plague of bad USB cables (power connection is good, but data lines aren't connected) going around Arduino circles. Try a different cable.