What version of Windows did you have on the PC when you ran the upgrade? was it Win XP, Vista or 7?
You would have been given the following options, Upgrade (keep all my programs and settings), upgrade (just upgrade Windows don't keep any programs or settings)or keep nothing (clean install of Windows.
Now if you have Win XP then think you can only do a clean install doesn't keep any of your programs, documents etc.
If you have chosen the 2nd option all your programs, documents etc. will be in a folder on your C drive called Windows.Old.
You are going to have to reinstall all your programs from the discs or by redownloading again.
BUT if you had Windows XP then it only did a clean install and don't think there will be a Windows.Old folder.
Did you not do a backup of your system before carrying out the upgrade to Win8 or do you have the original discs where you can restore your pc to it's factory installed state, you will still have to re install all your programs etc. Sorry but it's NOT MICROSOFTS SCREWUP, IT's YOUR'S UNOFORTUNATLY