There are 3 ways you can use to unlock the tablet without factory-resetting it:
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Send it to warranty or visit the shop where you acquired it.
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Use the code/pattern/password assigned and restore its functionality. This involves actually remembering the password.
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Visit a local mobile shop, and they will unlock it for a small fee.
These are the official ways, because if you attempt to factory reset it, all information contained on the tablet will be lost.