About security of my device Once my friend login his google account in my device.Then he cleared my phone data by using lost my device option.Now how to protect my device from this type of problem?? Help me
The best way to keep yourself from being in such a situation is you should never let somebody else login to your device. They can't use their account to wipe your phone if you don't let them login. Also, if you are going to let somebody login to your device(which you shouldn't do for security reasons), do it via incognito in the browser. If they wiped your phone then you should be fine to login with your google account and get a backup(hopefully).

Just like the only way to make sure your computer can never get malware is to make sure it never interacts with the outside world, the only way to make sure others can't use their google accounts to wipe your phone is to make sure their accounts don't have access to your phone.