Localhost:8888 now inactive after changing server name in Settings

I have been following some poor tutorials it seems. I was trying to go live from my local mamp setup for my website, and the initial step for one of the tutorials said to change your url settings for the local wordpress from localhost:8888 to the live url. Eventually the tutorial led me in the wrong direction or I screwed something else up. Now i want to change those url settings BACK to localhost:8888 but i can’t access the local wordpress login because it seems localhost:8888 is not responding. please help?