My Book External drive being detected as having no file table

Hi,
This drive is Western Digital External My Book Essential Edition. It was purchased because it is the main storage drive for my company's artwork and projects. It is constantly connected to either a mac or pc, depending on who is using it. As of yesterday, it is no longer working correctly. It connects to any computer, but is read as not having been formatted. I was considering disassembling the external in order to plug it in internally (it's a Serial ATA drive) and run chkdsk but I wanted to check first to see if it is even worth the trouble. It is essential that the data on this drive be recovered, and I would prefer to not send this in for data recovery. Too expensive! Any help would be appreciated.