a lot of people, myself included, germ the seeds in a paper towel before we put them into our meduim of choice... just take a paper towel, fold it into quarters, and wet it slightly.. place the seeds in the middle of the napkin.. i then take the napkin and place it inside of a plastic baggy.. i leave the bag open and place it on top of like a dvd player, cable box or stereo, and keep it pretty dark.. like cover it with something.. usually in a couple of days max, i will see the taproots coming out of the seeds and then i place the seeds carefully taproot down into my medium...
but to answer your ?'s... how cold was it at the window? it could take a week or longer to see seeds pop out of the soil if not germed before.. just keep the soil moist, not wet... and give them some more time... i would think if you don't see anything after two weeks, you pretty much could say that it is time to try again..
hope this helps you out some...