I would NOT run chkdks if the drive has problems. If the data is critical, I would immediatly try to image the drive to another working one. Take a look at your image and see if it is readable, if not try File system recovery software like R-Studio rtt.com on the image. You can try running a CHKDSK on the IMAGE but I would not recommend running it on the original drive if the data is important.
You may want to try removing th edrive from its enclosure and connecting directly to your PC.