first batch trouble

So I brewed my first partial mash saturday. Followed directions, two days later there is still no activity in the fermenter. I think I may have messed up the yeast. I followed dirwctions to make a "starter" but something is obviously wrong.
So my questions are: can i opwn the fermenter to see whats going on?
Can i put a new batch of yeast in and try to start over?
Any recomendations are appreciated.
Chris

What kind of yeast did you use? They say it can take 72 hours to see signs of visible fermentation. Yes you can open it and take a gravity reading to see where you are at. If and when you open the fermenter, look for a krausen ring on the edge of the bucket. It looks like dried gunk around the top edge of the beer. If there is a krausen ring then you missed the primary fermentation as sometimes they can also happen very fast.
Happy brewing
-Chris

I used dry yeast that came with kit. Ok great, thanks, i will let yall knowvthe outcome.