I guess I'm more concerned by what told you to clear the cookies from your browser? That's an odd thing to pop up, even with a hundred tabs open.
Another question is why were you keeping so many open tabs? Were you, as B. Diddy assumed, trying to use open tabs as bookmarks so you wouldn't lose the page, or were you on a pop up journey, where one page leads to another and another until you ended up with all of these pages open? If the latter that could be why you got that weird message to delete your cookies. Did you also get any pop ups for antivirus, malware or other scare tactic ads?
As intelligent_zombie stated if you didn't clear your history you should be able to find those pages again but you would have to go back to the day you opened it or last refreshed it n your history. You might be able to search your history if you remember the page's URL name. Otherwise, if you had a tab that you opened on the 4th of July and never closed it isn't going to show up in your recent history, you'd have to go back to your history for the 4th of July. This would be another argument for using bookmarks and favorites.
Good luck and best wishes.