Can´t find my usb device

Hi.
I can't find my usb device anywere in my macbook. I "pushed out" the Usb because it told me that it could loose stuff in it, if i just took it out. And now when i pluck my usb device again i can't find it. Help plz.

Sorry bad english

Try different USB port.
Try different USB device to check port.
Try USB on another computer to check device.

If your USB ports don't work, but your device is OK, then try this:

Reset the parameter random access memory (PRAM) and nonvolatile RAM (NVRAM) on your computer. Turn off your computer, then restart it and immediately press and hold the "Command," "Option," "P" and "R" keys on the keyboard. Release the keys after you hear the startup chime for the third time and your computer should boot normally.