If you are using Windows, go to My Computer and look for it as a hard drive.
If the external hard drive shows there, double click to open it.
Ooops, sounds like you may have already done that...
Did you have an icon for it on your task or tool bar? Double right click if its still there. Click Open or Run.
Go to RUN and type msconfig. See if it is on Start Menu.
Also, you might be able to access it through Windows Explorer.
Did you check your USB connection?
Also, USB sometimes does not have enough power, so it may require a PS/2 boosting connector or an Adapter. Also, check the connection of the Adapter and power strip its on.
Try going to SEARCH, pick Advanced Options, enter the letter of its drive before it was "lost" and look for a known file on the letter of the Maxtor drive.
DOOOG
Ps. did you add any other drives? Sometimes Lettering of drives can change.