Lost all USB on WIndows 7 PC

There is a free software called Repetier-Host - its relalted to 3D printers and connects by USB to the motherboard of the print.  I mentioned on a Faceboob page that I was having a problem getting  this programme to work.  A few wminutes later I  had a Private Message with a download link  and a message to  say it was the latest  upgrade - as its a free programme I saw no harm in this and downloaded the file. Despite the files title it  was not Repetier and  has it was being installed a Norton pop up advised a file  was not safe and had  been removed.  I have  uploaded teh file  named by Norton  - to Norton  to check it and deleted the application  which seems to be a scam.  However, about 3 days later  I  rebooted  the Windows 7 PC and found  no internet connection... no light on the USB  dongle then  trid the mouse to   click the  wifi icon to troubleshgoot... no mouse - no keyboard  no USB  ports working. I am not bright on computers but a friend  pointed me to a guy in  a local store and after 3.5 hours,  he gave  up and could find  nothing  to re-enable the USB  ports.Forgot to mention he  got into the  computer  by using  the old mouse and KB which  did not use USB and  those round  purple and green plastic  covers. Without a wifi connection - its virtually impossible ( for me) to get anything from Microsoft to  deal with USB  drivers... and Heur.AdvML.B  seems to responsible. 

Thats the background.... question is  what can I do  to get the damaged USB  drivers replaced by good ones -  and how do I get around  no USB access?