iPhone isn't recognized by iTunes on ANY computer

Ok so....
I updated iTunes on my Windows 7 computer and since then, my iPhone 4 isn't recognised by iTunes.
I tried resetting my iPhone which made things worse as now it isn't recognised by iTunes on ANY computer (Windows or Mac)
and as it is running an old version of iOS and has been reset, I cannot use my phone because I need to activate it with iTunes which wont recognise it!!

PLEASE HELP!!!!!