Many Android phone makers gives a specific guideline on this but in the absence of such, generally you:

1. Switch off the device

2. Hold the POWER key together with at least the down volume key to power the phone and start the resetting process.

3. A command-like window with sometimes a green text appears

4. Use the up/down volume keys to scroll screen and use the Power key to select.

5. Select WIPE DATA and the phone reboots after some few minutes to clear and reset your device memory.

If the above guide doesn’t work for your device, then we certainly must revisit point number 2. Note that this is because some Android versions like Gingerbread and dear old Froyo 2.2 will not go with the typical Hard reset method outlined above. Also most recent Samsung Galaxy smartphones may need another slight alteration in point number 2.

Alternatively try this for #2…

i. Power your device while simultaneously holding the Up and Down volume screen. Hold until blue screen appears

ii. If the above doesn’t work, try holding the Up volume key + Power key + Home key especially for Samsung Android smartphones.

iii. Some phones are so tricky, try this out yourself, try holding the up volume key or the down volume key or both together with the power key until the blue screen comes up!

There is really no one specified method that works for all Android devices!

See Source and full post here http://www.mymobnet.com/format-or-unlock-a-passwordpattern-locked-android-phone/

Moderator, I will appreciate if you push this to the front page so that more people will be helped, thanks.

Who no sabi this thing?

Igwevalentine:
Who no sabi this thing?

i wonder oh