I keep forgetting how to do this and searching for the answer on the web just leads you down a horrible twisty maze of passages all looking the same.
Your Google-Chrome session has become discombobulated and when you close the browser all your open tabs get lost. Lots of reasons why this can happen and most of them are not Chrome’s fault; last time for me, my disk was full.
When you resolve the issue that caused the lossage, you might be lucky and your open tabs come back automatically. More often than not they disappear and it is necessary to restore the open tabs from your sync account. That should be easy but where on earth is the magic button that does it?
I suspect Google are hiding this option deeper and deeper in the browser config because it is not used very often; fine, but how are you supposed to find it when you DO need it?
This should open a page in your browser listing the computers that sync to your account. Beside the name of each computer is a dropdown with an option to Open All; choose that and all your previously saved tabs come back.