I have a 2011 impala that I'm being told that I have gotten water in the motor and that it is locked and I now have to replace the motor how much does something like that generally cost?

$1500-$2000 for a used motor installed. More for a rebuilt motor.

in 2003 my factory rebuild was 7000. it ran good..i just was not happy that the motor was a older block than my original.

How did the water get into the motor? Cracked block, blown head gasket, flood, driving through high water and it got into the intake system? If the motor is full of water, the pistons will not move as water will not compress. Maybe remove the motor and have it rebuilt? Cost? Since this is a two year old car, does a warranty come into affect? Insurance? If it is that new of a car, get either a crate engine or a new motor if it can't be rebuilt. It depends on how the water got into the motor and the reason why it is frozen? A tiny bit more info would help here. If warranty or insurance, don't matter, have them do it. A rebuild is less money unless the block is damaged.