Lenovo P700i is an Android-based phone. This means that it can be unlocked using the Factory Reset operation. This method involves wiping all the custom settings and applications that have been installed by the user. If you have a SD card, the content will be preserved.
To proceed to unlock, turn off the phone and remove the battery for a few minutes. Put it back, then press the following key combination: Power button + Volume UP + Volume Down. Keep the buttons pressed until the Android logo appears. Using the Volume buttons, select Wipe Data/Factory Reset and confirm with the Power button. Reboot the device from the same menu and then wait. It should take a few minutes and once it comes back, configure the phone from the start and now you have access to your phone.