I can't make any changes to my contacts. I can't maneuver from one function to another. Basically the entire ap is useless. Any help out there?

I have not been able to add any new information to my contacts without it making completely arbitrary mistakes like erasing the name of the person who I try to add information about and sometimes making the change to every contact, assigning it to the wrong person. I can't get it off a screen once I'm on it. I cannot return to the alphabetical listings. I find this to be a useless but necessary ap. please help. The Apple help wasn't useful either