Admin stopped working on new install.

Hi Everbody,
Ok first website.....I'll admit but  the bell curve seems pretty short on this stuff thankfully!
I chose this software because it looks the easiest to use. and I''m stuck in a time frame to get something put together to sell my products online.
I installed the program and when it finishes installing there comes a page that says congrats. click here to view your site. and its the same old site.
so I when to the other url listed on the congrats page http:://mysite.com/admin which worked ok I got in and setup all my options and a few test products
but that was yesterday and now it won't let me back in to admin. I'm using the same user name and the same pw that I listed when installing with out a doubt. ( wrote them down naturally) I've used them several times yesterday.!

and the store front doesn't come up still. the software was installed in the public_html folder on mysite. and I see a few different files in there but i dont' see a way to make it work.  does this mean i need to uninstall and reinstall?