Sleeping too much can be a sign of a number of things, from plain old severe fatigue (have you been working a lot or keeping late hours?), to stress, to depression, to diabetes (high blood sugar levels can cause fatigue). Even a lingering infection or virus can cause severe fatigue. Have you been sick lately?
I would suggest going to your doctor and begin with a good, complete physical to rule out any physical causes. Once those are ruled out, you may want to consider the possibility of depression. You don't necessarily have to "feel down" to be depressed - one of the symptoms is changes in sleep - either sleeping too little or too much, as well as your comment about not wanting to go out of your room - the not wanting to participate in activities (could be because of the severe tiredness, but could also be a symptom of depression)
But definitely get checked out by your doctor and make sure they run some blood work, etc., to make sure all your levels are ok - perhaps even request they check your thyroid.
I hope you feel better soon!