Okay so i just switched the transmition in my sante fe and when i got the new one in the car wont start it will just startle.. I dont know whats going on. What do you think it is?

Not sure exactly what you are saying here as there appears to be a typo error. Are you saying that the engine rotates and turns over when you try to start it, but it does not "fire up" and run? If that is your problem, start by tracing every electrical component and wire in the engine compartment to make sure none of the wires or connectors have not been left unplugged or unattached from anyplace, and also check for burnt out fises. It sounds like something has been left unplugged or disconnected during the swap out. If all the connections are intact as they should be, then you need to double check that the flywheel has been bolted onto the torque converter ( you should be able to open the inspection plug on the housing at the bottom and see the flywheel, and then pull some plugs and rotate the engaging and flywheel by hand or by tapping the starter switch) and also make sure the starter is properly seated and bolted in. There is actually no reason that I know of that would cause an engine not to rotate after a transmission swap, and you can actually run an engine without a transmission in the car as long as the starter motor can be bolted onto the engine with the trans off the car. If everything I mentioned checks out, then it would appear to be a coincidental problem that may or may not have resulted from the trans swap out. In that case you need to check these 3 things: 1) make sure you have POWER from the battery out to everything in the car, (fuses, connectors, wires and cables) 2) Make sure you have fuel going to all the cylinders (it is possible the fuel rail electrical connectors to the fuel injectors were inadvertently left disconnected) 3) Spark to each cylinder (possibly left a connector to or from coil unplugged) Check it all out and get back to me please.