whatsapp.plist

hello every one i have a problem with whatsappwhere it stop working and asking me to re regestir again only promote me to install the lastest app version thats where i stuck my ios 5 is not compatiable with the latest app, upgrading my ios now is not an option and along the way i notice something intersting which is i can still get whatsapp message which get biuld up so i think that something can be done at the moment i open whatsapp.plist but i dont know how it work the only thing that i am sure of that jad and my my phone number is not found so i want help to rebuild my whatsapp.plist file in hope that will solve the problem thank you in advance