If this is BS feel free to move it.

Bear with me on this please. I am a complete techophobe and have had many inane computer probs solved here, so thought someone may know the answer to this too?

I have a Nokia mobile phone which I have dropped and the plastic bit covering the screen broke off and the plastic casing around it is shattered. I have sellotaped it back and it still works at the moment. I know I need to change it but don't want to get a new phone number.

Do I just have to buy any other Nokia to keep the same number? I know it has a Sim card, or imagine it does as I have heard people talk about them. But I ashamedly have never taken the back of my phone, I belong to the 'if it ain't broke don't fix it' generation.

If I go to a mobile phone shop and choose another Nokia phone, my model is no longer available I think, do I undo the back and take something out and put it in the new phone and it will work as though I am still using my old phone?

Thanks in advance.