Model not following the bones

I had made the armature and partially weight painted the model. I had went to pose mode and everything ran fine. Then I decided I’ll continue with the work on the next day. However, when I opened blender, weightpainted some more of the model and went to pose mode, none of the bones was followed by the model, even the ones which had been the previous time.
Ive been following this tutorial:
http://eklq.net/skinning-weight-painting-in-blender-2-5/

Is it possible that when you finished work the first day, you left the armature in a non-default pose? You know, Alt-G, Alt-S, Alt-R in Pose Mode to put the model back in the default pose?

If you did weight painting on the mesh while in a non-default pose, the results could be unpredictable.

Is it possible that when you finished work the first day, you left the armature in a non-default pose?
I dont know, Im not sure

If you did weight painting on the mesh while in a non-default pose, the results could be unpredictable.
How do I fix that?

Please anyone? I dont want to start all over again.

One thing to check would be that the armature modifier is still on the mesh and it’s set to vertex groups. If that’s not it, post the .blend file so someone can look at it. You might not be able to attach it here since your post count is low (anti-spam measure), if so, post it someplace and post a link…

I don’t agree with this. When I’m weight painting, I’m constantly posing the character to find problem areas and touch up the weight painting.

Can you post your blend file?