Iphoto problems.

Hi,

I tried to open Iphoto on my mac but it stuck in the black screen. When I force quit the app and reopen, it appears to be not responding ( wont even open ) but still cannot be forced quit again by using Cmd Alt Esc or whatsoever. Now I cannot shut down or restart the computer without pressing the start button. It's been like this for nearly a day.

Can somebody help me to fix this please? 😢😢

Many thanks!!!!