how to find the last time I used my usb drive? I used to have a Sandisk Ultra Fit 128GB stick plugged onto one of my USB ports of my MBP. I'm running OS X El Capitan (10.11). Today I found that my USB drive is missing. 

How do I find the last time that I used my pen drive so that I could get a sense of when I lost it? I have some very important data in it so I'm dying to find it somehow! Any help is greatly appreciated.

Edit: I'm pretty sure that I had and used it two days back.
Use the system.log. There you can find when your device has been disconnected. For more info: Is there a system log which displays which external media/storage devices were connected/disconnected from my system? If so, please advise me on how to do so.