please help me find my photos in el capitan - the screen comes up blank after update and restart - i need my photos I'm having a breakdown

I just updated from Yosemite to El Capitan so I had already made the move from iphoto to photos. When I updated and restarted my computer w/ the new uprade, I go to open my PHOTOS, and the screen is completely white with nothing there. I am freaking out - All the forums seem to reference people upset about going from iphoto to photos, but I had already made the move. Doesn't seem to be a way to update - I am freaking out I had thousands and thousands of pictures - someone please help!!!