Contacts not being displayed in contact list but appears when trying to save a contact I have Lenovo A6000+ smartphone. About 100 contacts have been removed when trying to backup contacts on SD card. But when I enter the phone no. of the removed contact, it reappears again in the contact list. 

what is the reason for this and how may this be resolved?
See if anything has changed in contact display settings. 
go to settings>contacts>contacts to display>and select "all"
Now it should show all your contacts.