everytime i open whatsapp the app appears on screen for like 1-2 seconds then it crashes with the message "unfortunately, whatsapp has stopped working". i tried opening it many times but it doesn't work. what do i do
The best thing to do is to go into settings, apps, look for whatsapp and press force stop, this will stop the application completely but won't clear your data.
I don't think so. Since it runs off an account it's like Skype or anything like that, your contacts should be saved. Maybe I'm wrong, sorry if I am.
It will, but it's the only possible way of thought, I had to reinstall an application when I had the same problem as you and the app has worked fine since.