If it is stuck in 4th, than it is stuck in 4th... If the push rod welds itself to the pressure plate or to the tranny side, than you can still go through gears, you just cant use you clutch, it will be stuck engaged(Doesnt Necessarily mean it wont shift). Try just using the shifter to see if it will pop out of gear, if not then you need to open up the clutch side and have a look. The shift shaft could be locked between two pins. None the less your gonna have to open it up.