Forum:Please Help!

I used a USB modding method to go back and help me out on one of Marcus' missions(accidentally tripped a point in "its like christmas") so all i did was go back and say that i havent accepted the mission yet but when i try to load my character it says "you cannot choose the same saved character as another player."

I really need help with this, this character was my pride and glory..

any suggestions or help of any kind would be greatly appreciated!