External hard drive is no longer connecting after Mavericks

Hi!

I have been using an eternal hardrive to back up with Time Machine with no problem until I upgraded to Mavericks....then everything went downhill. Now when I plug in my external hard drive it does not register or show at all. What is going on???

So frustrated with Mavericks, so many other complaints and frustrations but for now really want to solve this simple issue.

I have tried both USB ports and it just does not work.

Any suggestions?

Thank you,

Sarvasmarana