What could be wrong with a yellow lab 6 years old dog who is lethargic wont drink or eat go outside and acts scared?

Possibilities are; internal injury, poisoning, foreign body (swallowed) or infection, this condition requires further study by someone that could handle the dog if it wants to bite - which is common in a distressed animal. Get the dog somewhere it should be relaxed, then run hand gently and slowly over the whole beasty, if there is injury the dog will often react as you get to the area - Be careful even calm dogs react badly to pain. If its poison, typically rat bait; shakes/tremors in legs and body and eyes can red up and tongue can discolor/swell. Snake and spider bites often cause pain in the nearest joint (knee/ankle) If your missing a Golf ball or other stomach problem (as in twisted) only gentle massage will tell (dog reaction) Infection is spoted easily by temperature, but getting an accurate reading is difficult and needs an expeirenced hand