I have dead pixels all over my phone

First what happened before the issues started?? Was the screen replaced? If so make sure the connector are on correctly and clean of debris. if your phone is less than a year old take it to Apple Store to see what they can do. If it's older than a year buy a quality screen from Ifixit, follow the guides on the website. You will have to transfer the home button, and be very careful when opening the phone that you don't open to far and break the cable for the home button. Also on the iPhones the glass and LCD are glued together, making a glass or LCD replacement only impossible without expensive equipment!!