Transmission for 1999 I 30

[amarendra.sonti]

When i was trying to take my car out of parking lot, i gave some problem. Car was not moving even though i shifted the gears and it was giving loud noice when changing gear to Parking mode. I tried raising accelerator but no use. I got it towed to Garage. Mechanic is saying that my car axle came out but when i tried giving more accelerator caused damage to the transmission.
He says that the transmission has to be replaced now.

Is whatever mechanic saying true?
Then how much does it costs?

Please help!