Free apps are not getting installed on iphone6 ios9.1

Dear support,

i am unable to download free apps like facebook messenger,instagram etc on my i phone 6.

my i phone is having ios9.1, also some apps like facebook is showing update but when i am trying to update,its getting failed.

application can not be updated/downloaded this time message is coming on both the case.

please provide the solution to fix this issue.