My recollection is that WordPad saves to the last place you used.
WordPad is not part of Microsoft Office, but to determine where that documents are being saved, open WordPad (or Word, if that's what you actually are using), type a few random letters, and then use the "Save as" option. The location of the file will be shown in the box at the top:
You could also, of course, use Search if you remember the name of the file that you saved. Search in "All files and folders" and under "More advanced options" make sure that the boxes for "Search system folders", "Search hidden files and folders", and "Search subfolders" are all checked (and no other boxes are checked).