Assassin's Creed 4: Game will not play

I recently downloaded Assassin's Creed Black flag onto my HP desktop. I had it on pre-order and downloaded it immediately after it was released (I bought off amazon using Ubisoft, not steam). It worked completely fine up until about a week ago. I played it the day before leaving to visit family for the holiday and it worked fine, and was out there for about a week. The day after I returned I opened the game up, however it would not open. When I choose single player mode it pops up in the task bar *(attachment 1), but when I click on the icon a black screen shows for a couple seconds and then it returns to the screen I was just on. When I choose Multiplayer it just shows a message over a black background *(attachment 2) telling me something is wrong. I have also verified the game files *(attachment 3) and nothing appears to be wrong. Is there a way to fix this problem without having to uninstall and re-install the entire game, and would that even help?


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UPDATE:
I have tried many times to open just to see if it works because it worked the 5th time I tried, and it seems that for whatever reason about every 15-20 or so times I try to open it It opens properly once

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