ESATA to USB2 connection?

http://www.newegg.com/Product/Product.aspx?Item=N82E168...

This is probably what you are looking for.
However if the computer is no longer recognizing the external drive then you may have a problem with the drive , that's why before you start buying things it wiyld be a good idea to remove the hard drive from the external enclosure and plug it into the internal sata port to see if it is working. If you can't or don't know how to do that then take the cover off of the side of the computer and plug the e-sata cable directly into the motherboard , most motherboards have an e-sata port and in case you didn't know it's the one that the inside of the port looks like an L.

Update on the problem with the external drive: Last weekend, our son came out and had the accessories to plug the open existing hard drive into his computer and it wasn't recognized. The new drive was recognized on his computer. Put the new drive into the old case and it was only partially recognized by my computer but only when it was turned off. Turning it on, it no longer was recognized. Ordered a replacement case from Newegg and received it yesterday. Installed the new drive in the new case, plugged it in and put the power cable in and it was recognized instantly. Powered it up and Casper imaging software I had already installed recognized it as well and led me through steps to define whether or not to partition it and if so how large a partition did I want Casper to have. I did so and Casper is now formatting that partition. So both the electronics in the original case and the old hard drive had both gone bad. I will soon be back in business!