1996 Ford Mustang Stuck in 1st gear

I took off a little hard in 1st gear and I shifted into second but the car just revved up when I gave it gas. Well now the car is stuck in first gear. The clutch is working fine. I can drive it around in first gear but it won't actually go into another gear, and when I do move the shifter there is no resisitance at all. Almost like it's loose. My brother and I took the column apart and took the top of the transmission off because he was thinking maybe a linkage or something but we didn't see anything and we also made sure that the little ball at the end of shifter was still in the joint or cup or whatever you would call it. I need help please.