If you're trying to find a particular video you looked for, search history may help. Your search history lets you see what you previously searched for on YouTube.
To access your search history, click the down-arrow next to the Upload button, select Video Manager, then click Search History on the left side of the page.
You can also visit the search history page to remove individual searches, clear your entire history, or pause your history. It's likely that your browser also saves your search history, so learn how to clear your browser's history.