You have 2 options:
You can buy a new touchscreen and replace it yourself. Of course, as most people we see here who try this, you can break something else in the process. Then it's a matter of buying more parts, trying to replace then, breaking something else, etc., etc.
Or you can save money, time and frustration by bringing the phone into a good repair shop and having them replace the touch screen.
Assuming you didn't buy coverage which covers this kind of damage, in which case you find out which is cheaper - paying for it yourself or paying the deductible.
And once it''s fixed, spend the money for a good TPU (thermoplastic polyurethane) case with a silicone skin. They take a lot of the shock that the phone would normally get if you drop it - and good ones are in the $20 range.