Dell XPS 15 (Haswell) SD card reader not working anymore

I just got this new XPS 15 a week ago and was reading SD cards until about an hour ago. I removed a read SD card and entered a new one and the computer did not recognize it anymore. I tried the one that was read before and nothing anymore. I rebooted the laptop, but this did not help. Still no SD card is recognized anymore. Can anyone help me with this? Thanks.