How to get my SAturn 2001 SC1 to start again?

the switch needs to be coded to your automobiles ECU engine control unit

which means? and how do i get it coded?

Your old key has a tiny transmitter located inside the plastic. You have to transfer that code to your new key. Get some kind of a wedge (like opening a watch to replace battery) once you get i open you can sometimes transfer the whole insides to the new key ,, if not then it's necessary to hold the old and new key together and hope the old transmitter allows you to start ... once it's started go to WIKI for instructions transferring to your car

ok but the new ignition switch he put in came with keys to fit it so shouldnt they work?

No. Like those guys say the new key will not be recognized by the ECU

no, modern automobiles are not for the DIY automobile repairer this is to prevent theft of automobiles, so the next time your automobile breaks down send it to a specialist.

The ingnition needs 2 components to start... the mechanical key and the electronic Anti-Theft codr, That code is stored in the cars computer (like a password) the new key has no password but your old key still has your code, Put both keys close together so the computer see's the code (password) The computer becomes "Fat,Dumb and happy" Now follow my direction s on transferring the code to your new key

how do i get the code from the computer? where is the computer located?

You don't have to access the computer physically. https://www.google.com/search?q=2001+saturn+s-series+program+key&ie=utf-8&oe=utf-8

Link there and take you pick. Most of them probably won't work. You really need a dealer or a (hard to find) QUALIFIED locksmith

Have you even tried Tom's instructions?

I'll try again to explain. You are only working with the old and new keys. The old key came with the car and it has a code inside that little piece of plastic that has a hole in it for your key ring. If you pry the old key apart there is a tiny circuit board inside ... that small circuit board emits a signal that disables the anti-theft feature so you can start your car ( imagine a cell phone that will only ring when someone dials your number ... there must be a bazillion telephone numbers in the world but your phone ignores ever other number but yours ... that's how the anti-theft code inside the key works ... it's always transmitting a number but the cars computer won't let you start unless it dials only it's number. The old key has the correct number but the new key has no idea what number it needs to dial so the car will never disable the anti-theft safety. Now we need to trick the computer by holding the old key next to the new key so the computer thinks the old key is what you are using .. that disables the anti-theft and the car starts .... once the car starts there is a procedure that allows the new key to receive the old keys code ... you can even do more than one key so you have a spare ....OR ...you can have the car towed to a dealer,,, have the dealer do what I just told you to do and he will probably charge you about$350 (plus tow)