Android Lollipop is giving bugs on Lenovo TAB 2 A10-70F and you have to restore downgrade it to kitkat 4.4 for stable use. After restring if you want to root it on 4.4 kitkat here are simple one click rooter.
How to root Lenovo TAB 2 A10-70F on Kitkat 4.4
Download Kingroot One click root [latest]
Install this APK
You have now rooted Lenovo TAB 2 A10-70F on Kitkat 4.4