As you have replaced the external cable and the bracket (do you mean esata port card btw)
it may be the external HDD itself.
Please provide the brand and model name or number of the external HDD for us.
If you are by chance able to connect to the external HDD do the following for us;
Go to Start then to Search
Type in compmgmt.msc
and click Enter
On the left side click on Disk Management
On the right side you will see your hard drive.
Now I need you to take an expanded screenshot and attach it to your next reply.
To capture and post a screenshot;
Click on the ALT key + PRT SCR key..its on the top row..right hand side..now click on start...all programs...accessories...paint....left click in the white area ...press CTRL + V...click on file...click on save...save it to your desktop...name it something related to the screen your capturing... BE SURE TO SAVE IT AS A .JPG ...otherwise it may be to big to upload... then after typing in any response you have... click on browse...desktop...find the screenshot..select it and click on the upload button...then on the lower left...after it says upload successful...click on add reply like you normally would.Screenshot instructions are provided to assist those that may read this topic but are not yet aware of the how to.