The model has gone back to its origional pose.  If you do not know how to use graph or key frames, the simpleless way is to take your model to frame 100 and add a single pose to your library.  Click on add pose to library, then check the box that says multiple frames.  type in the both boxes frame 100 and save, this will save a single pose.  when adding back to scene on frame 101 make sure you check move all frames to single layer so you do not end up with multipul layers.  If you do not understand send me a pm