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.

Fix your audio drivers. Hardware problems can be caused by outdated or malfunctioning drivers. Make sure your audio driver is up to date and update it if needed. If that doesn't work, try uninstalling the audio driver (it will reinstall automatically).

Post questions, follow discussions and share your knowledge in the Outlook.com Community. You can give feedback by selecting Help from the top menu, then Feedback. If you need help with Outlook.com, you can read our self-help content, or get support via email.

If your system is asking you for your BitLocker recovery key, the following information may help you locate your recovery key and understand why you're being asked to provide it. Important: Microsoft support is unable to provide, or recreate, a lost BitLocker recovery key.

Hotmail is now Outlook.com. Learn how to sign in to access your Outlook.com, Hotmail, Live, or MSN email account.

The Microsoft Authenticator app helps you sign into your accounts when you're using two-step verification.

Block or unblock senders in Outlook. You can block messages from specific email addresses or domains from reaching your inbox. When you add an email address or domain to your blocked senders list, Outlook automatically moves messages from that sender to the Junk Email folder.

The VLOOKUP and HLOOKUP functions, together with INDEX and MATCH,  are some of the most useful functions in Excel. Note: The Lookup Wizard feature is no longer available in Excel. Here's an example of how to use VLOOKUP. =VLOOKUP (B2,C2:E7,3,TRUE) In this example, B2 is the first argument —an element of data that the function needs to work.

Change your password with your email provider. See the following sections for instructions on changing your email account password for several major email providers. If your email account provider isn't listed, contact your admin or the email provider's help desk.

To sign in to MSN just select Sign in at the top right hand side of the page and enter your Microsoft account information. You can also sign in to MSN by signing into Outlook, Office, OneDrive or other Microsoft services available on the MSN homepage.