Free Flash Drivers

Hi.
When I connect Pixel C to PC, PC does not recognize it and it does not appear even in device manager. (Even "unknown device" doesnt appear)
And my Pixel C says weird message "USB supplying power to attached device", which I havent never seen. I attached screenshots of that message.
And what is worse, charging Pixel C is also very unstable. Sometimes I can charge, but sometimes I cant charge.
Of course I cant use adb command. However, strangely, I can use fastboot command in bootloader.
I thought there was physical issue in USB type C terminal because even charging was unstable.
However, the fact that I can use fastboot command means there isnt always physical issue in USB terminal? Im confused.
I tried several kinds of USB cable, but same result. A weeks ago, there wasnt any problem in my Pixel C.
Please help me! What is the problem?
Pixel Cs USB terminal has broken? I dont want to believe, though.

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