Arduino void loop only running once - arduino

Question

The void loop is only running once. Please help. I am inexperienced with Arduino, so any help is much-appreciated. When I open the serial monitor I only see zero once. This code was working earlier today. Sorry if the solution is very simple. Some code has been removed to fit within post restrictions such as ints and ultrasonic declarations and includes.
void setup() {
Serial.begin(9600); //sets up Serial monitor
InfraredSeeker::Initialize();
}
void loop() {
if(u = 1) {
ang = uang;
} else{
ang = irang;
}
Serial.println(uang);
m1 = 200*cos((30-ang)*0.0174533);
m2 = 200*cos((270-ang)*0.0174533);
m3 = 200*cos((150-ang)*0.0174533);
InfraredResult InfraredBall = InfraredSeeker::ReadAC();
switch (InfraredBall.Direction) {
case 1:
irang = 160;
break;
case 2:
irang = 120;
break;
case 3:
irang = 90;
break;
case 4:
irang = 50;
break;
case 5:
irang = 0;
break;
case 6:
irang = 310;
break;
case 7:
irang = 270;
break;
case 8:
irang = 240;
break;
case 9:
irang = 200;
break;
case 0:
irang = 160;
break;
default:
break;
}
lultra = uleft.Ranging(CM);
rultra = urigth.Ranging(CM);
fultra = ufront.Ranging(CM);
if (lultra < 15){
u = 1;
uang = 270;
}
if (rultra < 15) {
u = 1;
uang = 90;
}
if (fultra < 15) {
u = 1;
uang = 180;
}
}