if i break my key would it make the engine lock up?
No, loss of oil pressure is the most common cause of engine locking up, other causes can be hydro-static lockup, that is when a lot of coolant or water is in one or more cylinders and it tries to come up on compression stroke and can't cause water will not compress.
the car isn't clicking its getting fuel but it want crank up , and i just change the the sensors and fuel pump , so i don't know why its not starting up
So does the engine actually turn over when you turn the key too crank position? If so then it is not locked up as your first post stated. Just what have you changed or replaced? There are a bunch of sensors and relays that can cause a no start? Have you got a code scanner? You may need to check for troubles codes and possibly "live data" streaming. So if you are going to buy one then make sure it can do all of that.
Looking for a Used Altima in your area?
CarGurus has 81,562 nationwide Altima listings starting at $1,200.
Search Nissan Altima Questions
Nissan Altima Experts
Related Models For Sale
Used Cars For Sale