I was able to talk with brynjolf in the ragged flagon, but can't seem to get back out of the ratway. The drawbridge near the entrance/ exit from the ratway is up and I can't figure out how to get back. Any help would be appreciated

Look for the lever to lower the drawbridge.

Its hidden in the dark

It took me a good ten minutes to find too, i just kept running around in circles and didnt find my way, then i just by chance noticed the lever.