Your car was stolen and you replaced the battery the car started but the radio didnt work nor would the car accelerate is this the engine immobilizer?

There are a couple of possibilities with the radio. It probably has an anti-theft function. What you can do depends on whether the radio came from the factory or was added later. Many radiOS have this function and when the battery was disconnected, the radio was programmed to assume that it has been stolen and locked up. On the factory radiOS, there is usually a code and a reset procedure in the owners manual, or if that is not available a dealer for that brand can reset it at a price, be sure to bring proof that you are the owner of the car. The radio may be after market, then you will have to go through the manufacturer, but you will first have to convince them that you are the owner of the radio. Usually there is some sort of registration. Some times it is just easier to get another radio. Often when a battery is disconnected, it is necessary to reset parts of the computer program. Usually ant this frequently takes a decent scan tool. The dealer or a competent shop would have one that will do the job and reflash the memory. There could be other problems, especially if their is some sort of security system on the car, but usually this keeps it from starting if it is factory or it will only run for a few seconds if after market. If you can keep the vehicle running by working the gas pedal, but it will not go any where, it probably needs to be reflashed with a scan tool.