I just got a Galaxy s4 in December and someone stepped on my phone cracking the bottom and making the bottom half unusable. How much would it cost to get this repaired?
Depends on if you have insurance. If you have accidental coverage, you can pay the deductible of about $99. Other wise it could be up to $200 to have Samsung repair it, or maybe a local screen repair shop would do it for less.
The screen is also starting to turn purple now. What do I do?
Well, seems like the digitizer is also damaged. I'd replace under insurance if possible, otherwise you could have a digitizer and screen replacement. At that point, if no insurance you either send to Samsung for an expensive repair or you buy another phone, either CPO, used, or off a cellphone site like Swappa.
The most important thing is to find someone that knows what they are doing with the repair. I had a Droid Maxx repaired for $225. With prices ranging as high as $375. I had places say they would replace the glass, it is not just that it is the entire top cover that the glass is enclosed in. Some smartphones you can get the parts online, but can be difficult.