drive clutch

i just got a t340 international crawler. it has been setting for a while. it will steer to the right but not the left. when i pull the lever to steer left it will sometimes completely stop. but the right lever will not make it steer. someone told me it was stuck. what can i do to break it loose or get it working.

I do not know that dozer, but I do know how it works. If you can turn right, and never left, then the left track clutch is frozen. That means it is in one of two states of continuous operation.
#1 The clutch pack (multi-disk high spring tension clutch) is rusted together between the driven and drive plates. It will require taking off the top final drive cover, and removing the clutch pack, and taking it apart. New disks may be needed, but cleaning and sanding them may work.
#2 The linkage connecting the clutch release yolk to the lever may be broken and or disconnected internally. This also requires removal of the cover.
The part of your somewhat confused (right left lever) description is the fact that you say it will sometimes completely stop.

If you try to turn left, and as you pull the lever back progressively harder, does the engine load down and start to work hard? If it does, and the engine stalls, then at least you know you have a good master clutch, and a good track brake.
If, however, the engine pulls down some, but keeps on running, the master clutch is toast, as well as the left track clutch being frozen.
If it has a torque converter (fluid coupling drive system), (and it might, I do not know that tractor) it can continue to run and be stopped.
If it does have the torque converter, then the master clutch may be OK, Either way, I believe it will be necessary to pull the top cover of of the finals. JimN