Android users normally secure their devices with a PIN, pattern, or full password. The phone isn’t useless when forget the unlock code - you can bypass it and get back in with Dr.Fone for Android. It's easy to use and safe for all your data.
Only workable for several Samsung phones:
Samsung Galaxy Note II, Note3, Note4, Note Edge, Note5;
Samsung Galaxy S3, S4, S4 Active, S4 Mini, S5 and more