thanks for any help!
Since finding files is a task within and special to an operating system (OS), you should at least mention which OS you are using. And to find it, you should also know, where you saved it. If you don’t know then nobody can help you. Assuming you are using Window, then open Windows Explorer and put the file name into the search field.
LibreOffice keeps a list of the most recently used documents, either look on the start page (with no document open) where their thumbnails are displayed, or go to menu File → Recent Documents and see the list there, sorted by recently used.