What are the reasons for a manual transmission car not being able to shift gears after starting?

[StLouis]

Manual transmission car not being able to shift gears after starting for the following reasons. P gear lock solenoid valve failure: For safety considerations, to prevent the vehicle from accidentally shifting into other gears when starting, the P gear solenoid valve needs to receive the signal from the brake pedal before it releases. Therefore, these two components are interconnected. If any one of them fails, it will result in the inability to push the gear lever out of P gear and shift into other gears. Internal failure of the gear lever: Internal gear wear of the gear lever causes the gear lever to get stuck, making it difficult to push or pull, thus leading to the inability to shift gears or difficulty in shifting. Incomplete clutch separation: This may be caused by a failure of the clutch disc and clutch pressure plate. Generally, this requires replacing the clutch three-piece set (friction disc, pressure plate, and release bearing). Transmission oil residue: Residue in the transmission oil affects the gear shifting of manual transmission cars.