Why isn't my phone finding sd card reader?

[Android Central Question]

I have an SD card reader that I use with my phone via the micro USB port. Yesterday it was working fine, then in an instant it stopped working. It doesn't even recognize that the reader is plugged into my phone. The phone still charges so the port seems to be working. I plugged the SD reader into another phone and it worked and I was able to see the pictures from my SD card. I cleaned the port out as well as I could. I'm stumped.