Locked out of Galaxy S Duos - Failed lock pattern
Try all the methods in a similar question on here: Izzy's Answer on Unlocking Android Devices via Google, ADB, and Recovery - Android Enthusiasts

There are almost 10 angles to work from running 3 pages long, it is too much to quote here and all credit goes to Izzy for spending a lot of time working up that answer.

If none of those work, please revise your answer to include any errors you encountered and whether your device is rooted, knowledge of installed Android version, build number, etc.

Hope this helps,