Unexpectedly, Outlook messages no longer open, if they contain an attachment in the form of Word or an Excel document. When I click on the received message, Outlook writes an error that there is no corresponding handler, although Word and Excel are installed. Than this to open? Previously, everything worked fine.

Restoring Your Backup with pst fix
1. Copy the backup file to your computer. If the backup file is on a USB drive, disc, or uploaded to cloud storage, you'll want to copy it onto the computer's local storage first. You can place the file anywhere, such as on your desktop or in your Documents folder.
2. Click the File tab or Office button.
3. Select "Open & Export" or "Open." You'll see several options.
4. Click "Open Outlook Data File." This will open the file browser.
5. Browse for the data file. Navigate to the data file that you copied back to your local storage. Select it and click "Open" to load the file.
http://www.wikihow.com/Back-Up-Microsoft-Outlook
https://outlook.recoverytoolbox.com/fix-pst-file/