Thanks a lot Scorpius.Deleting the chats.db file solved the problem.But i encountered another problem ,when i lunch yappari it open and try to connect to the internet ,when it is connected it log me in,and exist itself. But i notice that the yappari logo still appear in my home screen beside my battery logo.But i can't chat with it and it still show that i have login.Pls tell me What i can do to fix this problem .