Hello, if your car is in some kind of "limp" or "protection" mode, then there is a problem that must be diagnosed and fixed before it will work. There is absolutely no way of knowing what is going on from here; it will require hands on testing. There are quite a few possible causes.
Use this link to find some shops near you that can help with your concern:
www.repairpal.com/repair-shops
RepairPal Certified shops can diagnose and repair your 2012 Hyundai Veloster. They provide transparent pricing with a minimum 12-month or 12,000-mile warranty on repairs and services.