Unlock android phone with forgotten password and attached gmail account details too
If you don't worry for the data of your phone the everything will be easier.First of all turn off the device.Then open it again, wait 3 seconds and then press the power button and the volume up or down(the reboot may differ from phone to phone) Then, at the reboot you will be able to use it only with the up and down volume buttons.Reset the phone and everything will be deleted (even the password) For more information check here : http://www.greenbot.com/article/2458403/how-to-perform-a-factory-reset-on-your-android-phone-or-tablet.html