To help me understand and offer advice, please tell me:
* What gear is the transmission stuck in? Is it a specific gear, or does it feel like it's not shifting at all?
* What happens when you try to shift? Does the shifter move freely, or does it feel like it's stuck?
* Do you hear any unusual noises? For example, grinding, clunking, or whining sounds?
* Have you noticed any other symptoms? For example, slipping gears, rough shifting, or a flashing transmission light on the dashboard?
* What have you done to try and fix the problem?
Once I have this information, I can give you some possible causes and suggestions for troubleshooting.
Please note: I am not a mechanic and cannot provide specific repair instructions. If you are unsure about anything, it's best to consult a qualified mechanic.