Volume control problem

[AC Question]

Mine is lenovo tab 2 yoga....let me explain my problem....whenever I make call or receive a call on Facebook messenger everything is fine but when I finish the conversation and hung up my volume becomes neutral in other words it's stops working...there is sound but the volume buttons don't respond...then I have to make a call and immediately I have to hung up for making the volume buttons work.....this is giving me headache I don't know how to solve this problem ...I had Dell venue 8 tab before and that too had the same problem...