Welcome to the Seven Forums.
Kindly fill up your System Specs to the extent possible. There are plenty of repair options in W 7 to restore your system. Either read at Tutorial search - Windows 7 Forums
for all that can be done or read at Repair Install
in the Tutorials.
However I always prefer to reinstall W 7 afresh if the system gets messed up like yours has. That I find the best thing to do.
With so much written about the inefficacy of McAfee on these Forums I wonder why you use it. Either install MSE of Avast! A-V instead of McAfee.