Let's try these simple steps and see if it works for your pen drive:
1. Try using this pen drive with another computer (a friend's computer or home computer).
2. If it works in another computer try to copy all the files from it and then format it.
3. If the pen drive is not detected in any computer, check in the Disk Management if it is detected. To check in disk management follow the below mentioned steps:
a. Right click "My Computer" icon on the desktop.
b. Select "Manage".
c. Click "Disk Management" from the right pane.
d. Check in the bottom of the window that opens. The size of all the disk drives and their graphical representations must be listed.
e. Check if your pen drive shows here.
4. Try to format the Pen Drive from here and see if you can.
Do reply with results.