On most Android phones you can enter the recovery mode by turning your phone off, then pressing and holding the power and volume up button until your phone boots into recovery mode. From there, you'll have to find some option to wipe your data, which results in your phone being reset to factory settings. Please note, that all your data, which isn't backed up in a cloud will be lost by doing this. After wiping all the data, you can log in with your Google Account again and set a new Lock Screen Pattern / Password / Pin.
Hope this helps!
For assistance, please visit one of our authorized Service Centers to check it for you. You may refer to the link which will guide you to the nearest service center to your location https://www.samsung.com/ae/support/service-center/
Kindly follow the below steps:
- Unlock your mobile device using the Find My Mobile feature.
- The mobile device must be turned on.
- Mobile device must be connected to Wi-Fi or a mobile network.
- Your Samsung account must be registered on your mobile device and have the Remote unlock option enabled.