random() always giving the same result, used randomseed()

What is the code supposed to do?

Call randomseed only once but call random every time you want a new number... here it seems you generate only one random number - but unsure as your code is a snippet that won’t compile

Go read the documentation and see the example

long randNumber;

void setup(){
  Serial.begin(115200);
  randomSeed(analogRead(0));
}

void loop() {
  randNumber = random(50,300); // generate  a random number between 50 and 299
  Serial.println(randNumber); 
  delay(1000);
}