I have a problem with my HDD. The drive (WD External HDD 1TB) was working fine as of yesterday. Today when I reconnected the external drive to my laptop, it powers up but isnt showing in "My Computer". Went to device manager and it says its listed there and states the device is working properly. Went to disk management but it does not show up there. As a result have not been able to read or write any data to the hard drive.

From your description it appears that your drive is failing, possibly due to bad sectors. You can check if there are problems with the drive using the free trial version of http://www.hdtune.com/

If it checks out ok then you can try to recover your lost partition with Testdisk its free http://www.cgsecurity.org/wiki/TestDisk

Or if you need data recovery help this a good choice for low cost and fast data recovery. All data recovery work is performed by an experienced tech remotely over the Internet from a boot cd that you download and the best part is they just ask for donations: http://FreeDataRecovery.us