Join Date:Joined: Nov 2011
First, boot into recovery (the 'Volume + Power + Home Button' thing) & try a factory reset. If the problem persists, the only way you're fixing it is by flashing a stock rom with Odin.
As you can't seem to get your PC & phone to recognise each other, you need to find Hopper8's 'Odin troubleshooting' thread stickied in General, and do as many of the troubleshooting steps in that thread as many times as you need to until you get a successful flash of stock.
This is the only way you'll be fixing your phone for your 'something in two days'.