I have a polaris trailblazer 250 and I had to pull start it a few times. Finally bought a new battery and installed it. Still won't start. Any ideas???

Sounds like the most common ATV problem, carburetor. Since you have to take it apart anyway, get a rebuild kit with new float and throttle spring. Ensure you replace the keeper clip on the needle valve on the same groove for the throttle. Don't mix up the primary and secondary jets, and be careful about bending the float arm... support it without using the float itself as a gripping place as the arm will break off. (Motorcycle shops have a special tool for doing this and can get it very accurate.) Write down the mixture measurements (number of screws turns) so you have a place to start from... use 1/8 screw turns until the engine just skips a little bit when idling... it will smooth out when adding throttle. The choke is intended to be used when starting. Check any fault codes and instrument lights.