fermentation problems

I have had the wort at 68 degrees for three days in my fermentor but there has been no activity on the airlock.  I added the yeast properly after hydrating it and I cant figure out what is wrong.  Should I repitch?  How do I do that?

Is there foam on the surface of the wort? If so, you may have a leaky seal on your fermenter somewhere, and the CO2 is taking the easy way out instead of going through the airlock. No harm to the beer.
If there's no visible fermentation at all, definitely repitch. I assume you're using dry yeast... get two presh packets and just dump 'em in. No need to hydrate. Shake or stir your wort to aerate the hell out of it.

thank  you.  Its in a plastic (food grade) bin so its tough to tell exactly what is going on in there but there definitely looks to be a thing of foam up top.  The last batch I had in there was very strong and popped the lid off of it so maybe there is a leak.  What do you think about me transferring it to secondary fermentation in the glass carboy?  Should I throw another bag of yeast in there anyway?

Go ahead and rack it to a carboy once fermentation has slowed down some. Tho' it may be hard to tell when that is, since your airlock isn't bubbling. Crack the lid and give it a peek, it won't hurt anything.
If your beer is actively fermenting, there's little point in pitching more yeast.

I don't get it.  How can the previous batch POP the lid off if you have an airlock?  I should just bubble like crazy.  If its violent enough, it'll blow the water out of the air lock and you will have to put more in it.  If it POPs off the lid, then either you are not securing the cover well enough, or the airlock is plugged.  Did you check the airlock?  Try sticking it in a running stream of water from your faucet, water should flow through easily.  This might also explain why you don't see bublles and the CO2 is squeezing out the lid instead.

Just thoughts.

yeah, the airlock clogged at night while i was sleeping and when I woke up, the lid had been blown off and foam was all over.  It surprised me too.  I now know that avoiding that is the reason people use blowoff tubes