It stucked

[agn]

By mistake it locked and it needs Google account password and username or answering the question. I fill it correctly both of them but it didn't open. What might be the problem?

[Uliwooly]

You have 2 options 

1) try to remember the password 

or 

2) you will have to reset your phone

[Uliwooly]

http://talk.sonymobile.com/t5/Xperia-M-M-dual/How-to-reset-xperia-u-hard-factory-reset-forgot-the-pa...