Use this app to try to recover lost files that have been deleted from your local storage device (including internal drives, external drives, and USB devices) and can’t be restored from the Recycle Bin.

Some Office 2019, Office 2016, and Office 2013 products come with a product key. If yours did, before installing Microsoft 365 for the first time, sign in with an existing or new Microsoft account and enter your product key at office.com/setup. Redeeming your key is what links your account with Microsoft 365 so you only have to do this once.

Codecs in Media Player. Windows 11 Windows 10. Codecs allow you to play different formats of audio and video files. Media Player supports a wide variety of codecs. Most are included out of the box; some additional codecs can be installed from the Microsoft Store.

Find your BitLocker recovery key. A BitLocker recovery key is needed when BitLocker can’t automatically unlock an encrypted drive in Windows. This key, which is a 48-digit number, is used to regain access to the drive.

You can't open the following file formats in PowerPoint for the web, but you can open a .pptx, .ppsx, or .odp file and then use Download As to save a presentation in these formats: .jpg (When you choose this format, each slide in the presentation is saved as an individual .jpg image file.)

Cast to a display from a Windows PC. You can wirelessly connect your PC to a TV, projector, or other kind of external display that supports Miracast. Turn on your TV, projector, or other display. If you're using a Miracast dongle or adapter, make sure it's plugged in to the display.

How to play MP4 files in Windows 10. On a PC running Windows 10, select Start > File Explorer, or select File Explorer from the taskbar. Press and hold (or right-click) the MP4 file you want to play, select Open with, and then choose your preferred file player from the list of applications. Was this information helpful?

Contact Microsoft Support. Find solutions to common problems, or get help from a support agent.

Windows 文件名包含由句点分隔的两个部分：第一部分是文件名，第二部分是定义文件类型的三字符扩展名或四字符扩展名。. 例如，在“expenses.xlsx”中，文件名的第一部分是“expenses”，扩展名为“xlsx”。. 扩展名告诉计算机哪个创建的应用程序或者哪个其他程序 ...

本文介绍如何在 Windows 8.1、Windows 8、Windows 7 或 Windows Vista 中使用系统文件检查器工具来解决丢失或损坏的系统文件的问题。.