How to fix a smashed iPhone 4?

I was at a party and i dropped my phone and its all smashed i'm only 13 and i don't want to tell my mum and dad because they will say i have to go back to my blackberry is there anyway i can fix it easily and cheap or how can i tell them without them being mad?

If your contract is up then 4S is free on a new 2 year contract, and you can even trade in the 4 (even damaged they will give you something for it at least), so thats a good option and easy way to upgrade.

Is your phone insured? I have good news and bad…
Good - You may be able to get a new replacement phone by filling out a repair/replacement form
Whether the phone is in your name or your parents name -
In your name: you may be able to do this on your own if you have a personal ID, if you don't your parents might be notified since you are 13 yrs old.
It would be better for you to tell your parents rather than have someone else do it for you. Hearing what happened from someone else will only make them angrier, it is way better to hear from you.
Bad news: If your phone is in their name, then they will find out whether you tell them or not, your best choice no matter how hard it may be, would to be come clean now rather than having them find out later on, and have them angrier because you didn't confide in them in the beginning.