I cannot download any app from app store the iphone show this letter “your account has been locked”

If this is in the iTunes/App Store, see the 3rd link.

If your Apple ID is locked or disabled - Apple Support.       

If you have changed your ID or password, have you followed the steps in this article?

What to do after you change your Apple ID or password - Apple Support.      

See the Apple Support article(s) below. 

If you see a message that says 'Your account has been disabled in the App Store and iTunes' - Apple Support.    

Contact iTunes Support for assistance. See the Apple Support articles below for contact information.   

iTunes Support – world wide 

Apple Support schedule phone call     

Billings and Subscriptions 

If necessary, try Twitter

https://twitter.com/AppleSupport.