There are better ways to search in SharePoint 2013 than ever before.
When searching for a PowerPoint presentation, type in as much as you can remember about the title or subject in the Search box. Then, on the left, look for refiners by Result type. By choosing PowerPoint, you’ll only see presentations. You can also refine by Author and Modified Date. These are all located on the left of your search results in SharePoint 2013 where you would normally expect to see the Quick Launch menu.
You can always clear a refiner by selecting All under the refiner title.