Im not sure if I need a sensor

someone changed the wall outlet because it didnt fit the cord on the dryer but the idiot didnt hook the ground to anything. When I plugged it up and ran it, it spun really fast and then cut off. Then it didnt run anymore. So I changed the outlet back and changed the cord to fit the original outlet. It turns on and runs now but its not blowing any heat. It blows air because I took off the exhaust hose to check, its just not blowing any heat. The same idiot who broke it told me its probably the sensor. Can someone help me please?