Wont start

I don't know what testing you've done? How long since a tune-up? Is the vehicle computer controlled? Battery has a full charge and battery cables/connections all good. Have a helper crank it while you visually check for spark at the plugs. If spark, then check fuel. If a carb engine, cold engine,you can take fuel line loose at carb, aim into container, bump the starter, see if gas comes out of fuel line. If it doesn't maybe something wrong with fuel pump or fuel lines. Just to add, spark timing and valve timing are important.