Issue with a Nexus S face unlock & lock pattern.

[Google Nexus]

While exploring around my first Android phone Google Nexus other day I came across Face unlock, which I found cool enough to try.

But after 30mins, when I picked it up, Nexus couldn't identify my face & asked for lock pattern, which I can't recall anymore. Now am stuck on lock pattern screen & unable to get in. Also, after several failed attempts face unlock disappears & only provides lock pattern option to get in.

Somehow, today it identified my face & allowed me to get in & first thing that I wanted to do was to disable face unlock, but before doing that it asks for same unlock pattern, which I can't recall.

Now that it is stuck again on lock pattern, What are my options now?
If I'm able to get in via face unlock, what is the first thing I should do? OR
If it does not get in, what can I do to get rid of this?

Please help, am new to Android device, but I love Google & Android & don't want to spoil my first experience. Feel free to ask me any questions if that helps in getting out of it. Thanking in advance

 

[Baconator]

Maybe a factory reset.

 

[Google Nexus]

Somehow, it accepted my face this morning again & have face unlocked device with me.

Before doing a factory reset, If I take a backup image of whole OS, can I restore it after factory reset. If yes, how and through which app this would be possible.

Thank you.

 

[zorak950]

If you fail the pattern unlock enough times, it should just ask for your Google password instead.

Yeah, the Nexus S doesn't work very well with Face Unlock. There's a good reason that feature was left out of the official NS ICS build.

 

[Google Nexus]

Either I was able to recall the right lock pattern or it is Nexus bug, I was able to go through the lock pattern screen finally & disabled it. Phew..

Now, I would like to take a backup of Nexus, so in future If something goes wrong I can just recover the whole OS image and get over with any issue that is taking away my time.

What is the best way to go for OS image backup? This device is rooted, so I believe I should be able to do this with more control compared to non-rooted devices.
Which app to use? And how to recover this image, if something goes wrong?