Try this: Press RESET, then button B (the middle one). You should see two choices on the screen: RESET and DOWNLOAD. Choose DOWNLOAD. This should bring your tama back to the last major event in its life (waking up, changing to the next stage, etc.).
Well one day i took mine to the park and my dog barried it ne way it got sand in it and froze so i took it a part and blew out the sand so maybe yours has somthin in it.......