It probably varies a lot between the different ad blockers, but I can tell you what I did with uBlock.
There is a little shield for uBlock that pops up in the Chrome browser navigation bar. If I click on that shield I can un-block ads for whatever site I am on at the time. I also discovered after a while that I could turn the ad blocker back on again after I got Photobucket working again. Hard to say for sure, but maybe letting some ads through cleared a bad cookie. You could try another browser. I stumbled upon the solution to my problem when I realized the other browser worked but didn't have an ad blocker. Another thing to try if this doesn't work would be to remove Photobucket specific cookies.
