I had the same problem and searching on google has led me to here multiple times and all the solutions that worked for other people unfortunately did not work for me. :/
If you are in the same situation perhaps this way might help you.
I have sony viao vgn-nr430e. My problem was the
driver for "Mass storage controller" was not installed after i upgraded. But you can find the
driver here -
http://www.4shared.com/file/ObeQUyTl/Texas_Instruments_PCIxx21_Flas.htm
(Texas instrument seems to have taken it out from their site or something, but luckily someone uploaded it to 4shared)
After that you go to
control panel > device manager> right click on mass storage device> update the
driver> select browse folder> select the folder containing the file you just downloaded.
Hopefully this works.