minecraft not launching

whenever I click the minecraft launcher it will bring me onto the launcher screen as it should when I click play it will start to launch then says it hit an error locating a file i've tried everything I can think of deleting and reinstalling and all it just wont launch. when the error comes up it gives me a url as well when I copy and paste it into google it downloads a file but ive don't it about 10 times and it still wont work please help