Microsoft stopped me using my Office 2019 program today.

Hi B2B PRO,

Sorry to hear that your Office 2019 installation has suddenly stopped working.

Before spending time trying to locate the original product key, I would like to make you aware of a recently acknowledged Microsoft issue that may be related to what you are experiencing. Microsoft has reported that update KB5002907 caused some Office 2016 and Office 2019 installations to appear unlicensed or become unusable on certain devices, and the rollout of the update has since been paused.

More information: https://support.microsoft.com/en-us/servicing/os/microsoft-365/kb5002907-optional-update-for-out-of-date-microsoft-365-apps-installations

According to Microsoft's guidance, affected users may need to reactivate their purchased Office product, and in rare cases reinstall Office if it was removed by the issue.

If reinstallation becomes necessary, you may not need the original product key if your Office 2019 license was associated with a Microsoft account when it was first activated. In that case, you can sign in to your Microsoft account and check whether the license appears under Services & subscriptions, then reinstall Office from there. If the license is not associated with a Microsoft account and the original product key is unavailable, you may need to locate the proof of purchase, product packaging, retailer confirmation email, or contact Microsoft Support for licensing assistance.