iPhoto won't update after OS update

Hello, I updated to Yosemite last month and found that I had to update a number of apps for them to work with Yosemite. One of them, iPhoto, will not update and won't open until it does. When I try to update, the pop up box says "temporarily unavailable, try again later". I have tried updating "later" for several weeks now. Is there a fix for this or should I return to the previous OS?

via ehMac.ca http://ift.tt/1MMCBM6