I've been experimenting with my arduino and everything has been working just fine for a few weeks but suddenly today, I am no longer able to see it under ports. I don't hear any windows "connect sound" when I plug it into any computer (tried on several computers that have Arduino installed), and I tried a brand new usb cable on it too. The only thing I can think of that could've caused this is that I might've made some sort of improper circuit configuration which smoked the USB type B port on the arduino.
I was working on a project that involved a servo, but I wanted a separate power supply, so I used two 9V batteries to create an 18V supply and a voltage regulator to step down to 6V which connected to the servo. The pwm cable of the servo is connected straight to the board. I had to connect the ground of the 18V supply to get the motor to actually work. However, the arduino was still powered off of the computer. After testing the motor successfully, next time I plugged it in, the device didn't get recognized and here I am. However, the arduino still receives power from the computer and moves the motor back and forth when plugged in, running the same sketch that was last on it. I'm wondering if I should've connected the ground of the regulated 6V supply (yellow wire) instead of the ground of the 18V supply.... I added a link to a picture of my circuit. I appreciate any help you guys give!