Looks Like you have got problem while importing Standard Assets. Re-importing it will solve your problem.
Help please, I am not getting any response on my question, so I am posting a link to my question here.
https://answers.unity.com/questions/1629429/why-crossplatform-input-joystick-behaving-weirdly.html
Sorry, Abubakrkhan. I don’t want to be rude to post question link in your post. But I desperately need to know the answer. Any Help is greatly appreciated. Thanks.