[Q] Screen locked, and cannot sign-in

My brother entered the pattern too many times, wrong of course

Now the phone is locked and asking me to log-in, Wi-Fi is ON and connected, but the account is not signing in !

I can sign in from the PC normally, while I can't on my phone !

I have too many contacts saved on the phone's memory.

How can I unlock the phone without losing information, weather contacts or applications' settings ?