Starters will go dorment after they sit in a fridge for a forgotten period of time. Stir it up good n feed it like ya normally would, be patient it may take 3 or 4 days before ya see any bubbles at all. If it bubbles just a little after a week, split it in two parts n feed both, one or the other shoud kick off, I've had starters sit for near a year n kick off after a couple days with a good feeding, warm water n temps to reactivate it. Ya can even put in a little dry yeast if ya want to get things going, starters are usually just a wild strain of yeast or yeast like bacteria that yer just keeping handy, another trick is to use water from boiled(cooled off of course)potatos mixed with yer sugar to feed the mix