Dropped iPhone 4s & screen is blank. How can I fix it?

I accidently dropped i iPhone 4s & when I picked it up it had a crack on the front near the camera. The screen was blank y, you couldn't see anything, when I put it on silent you can feel it vibrate. I tried to fix it by looking it up online but it still doesn't work. I opened the phone & a nail was off but I fixed it, I checked closely & nothing was wrong. I need help fixing it. Does anybody have any advice on fixing my phone so it can go back to normal?

If you found a nail inside your iPhone then you have a screw loose…

Seriously, though, "I checked closely & nothing was wrong". No, you checked closely but evidently didn't identify what was wrong because you still have a non-working phone.

Other than that, it's clear that you lack the diagnostic knowledge and specialist tools required to identify faults with a very complex piece of technology.

You could try replacing the front screen as there's a crack which might be the cause, but it's a gamble and you could end up wasting money on a phone which isn't worth a great deal any more. So you have two choices: take it to a repair shop and pay for whatever tests need doing to diagnose the fault (some might do that part of the work free, but they'll get the cost back on what they charge for the repair), or you could sell yours "as is" for spares or repairs and then use the money towards another iP4s in fully working condition. The cost difference may well work out similar to or less than the cost of repairing what you now have. If you're prepared to do without Siri, then the iP4 is even cheaper and for most purposes every bit as good as an iP4s.