Hello ieatmother, thanks for reaching out to us and welcome to the forums.
Have you just purchased the game or have you owned the game for a while and this has just started happening?
First thing I would try would be to open Task Manager and view your performance tab when launching the game, what percentage is your CPU and memory?
Try verifying your games files first, this will correct and missing or corrupted game files that may stop the game from launching correctly.
Here are some instructions on how to do this in Ubisoft Connect -
https://support.ubisoft.com/en-gb/Article/000060529
Here are some instructions on how to do this in Steam -
https://support.steampowered.com/kb_...2037-QEUH-3335