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 might be prompted for the BitLocker recovery key during startup, due to a security risk or hardware change:

Learn more about product keys, Workplace Discount Program, and volume licenses. 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.

You can use installation media (a USB flash drive or DVD) to install a new copy of Windows, perform a clean installation, or reinstall Windows. To create installation media, go to the software download website, where you'll find step-by-step instructions.

How malware can infect your device. Microsoft security help and learning. If you suspect that your device may have malware you should have Microsoft Defender run a scan. Here's how to do that on Windows, Mac, or Android.

If your purchase of Office or Microsoft 365 came with a product key, you enter your product key on one of the websites listed below for your product. After you enter your key, you can download and install Office, or you can renew your Microsoft 365 subscription. Tip: Get tech expertise with Business Assist.

If you can't sign in to your Outlook.com, Hotmail, Live, or MSN email account, or you're not sure how to sign in or sign out, here are some solutions.

Change from a 32-bit version to a 64-bit version or vice versa. Activate Windows. Fix Bluetooth problems in Windows. Learn how to install, reinstall, or activate Microsoft 365 or Office 2019 on a PC or Mac.

Automatically update Windows 10, Windows 11, and Surface drivers and firmware. After following the preparation steps, see Update Windows to learn how to check for updates and install them. Or select the Check for Windows updates button below to open Windows Update in Settings. Check for Windows updates.

If you get an email about unusual activity on your Microsoft account, or if you’re worried that someone else might have used your account, go to the Recent activity page. You’ll see when your Microsoft account was signed in during the last 30 days, along with any device or app-specific info.

If you're trying to add your Outlook.com account to Outlook or another mail app, you might need the POP, IMAP, or SMTP settings. You can find them below or by viewing them in your Outlook.com settings.