1996 3.8 mustang manual transmission stuck in 4th

For about 3 weeks i had problems getting into and out of gears but it was very off and on that it would do this. Then it became stuck in 4th gear and will not come out. It will drive fine when in range of 4th gear and the clutch pedal will still put it in neutral. I have a B&M shifter. I have tried to turn the car off and take it out of gear but it did not work. Any ideas?? Thanks