How to fix my outlook which is failing to open

Try these fixes in order:

1. Repair Office first.
   • Go to Settings > Apps > Installed apps.
   • Find Microsoft Office.
   • Select Modify.
   • Run Quick Repair first.
   • If that does not help, run Online Repair.
   • Note: Online Repair reinstalls Office and requires an internet connection.
2. Start Outlook in safe mode.
   • Press Windows key + R.
   • Type Outlook /safe and select OK.
   • In Choose Profiles, accept the default Outlook profile and select OK.
   • If prompted, enter the password and select Accept.
   • If Outlook opens in safe mode, the problem is likely an add-in.
3. Disable Outlook add-ins if safe mode works.
   • In Outlook, go to File > Options > Add-ins.
   • At the bottom, confirm Manage shows COM Add-ins, then select Go.
   • Clear all selected add-ins, then select OK.
   • Restart Outlook normally.
   • If Outlook opens, re-enable add-ins one at a time to find the one causing the problem.
   • Do not delete add-ins during troubleshooting; disable them only.
4. Reset the navigation pane.
   • Close Outlook.
   • Press Windows key + R.
   • Type Outlook.exe /resetnavpane and select OK.
   • This removes navigation pane customizations.
5. Create a new Outlook profile.
   • A corrupted profile can prevent Outlook from opening.
   • Create a new profile, then restart Outlook and choose the new profile in the Choose Profile dialog.
   • If Outlook starts normally with the new profile, the old profile was corrupted.
   • Warning: if removing a profile later, back up data files first. Removing a profile deletes offline cached content.
6. Repair Outlook data files.
   • Exit Outlook.
   • Run the Inbox Repair Tool (scanpst.exe) using the instructions in Repair Outlook Data Files (.pst and .ost).
7. If the exact message is: "Something is wrong with one of your data files and Outlook needs to close"
   • Update Outlook from File > Office Account > Update Options > Update Now.
   • That issue was fixed in Monthly Channel Version 2005 Build 12827.20470 and higher.
   • Registry workaround exists, but it is risky because incorrect registry changes can cause serious problems.
8. If using Microsoft 365 on Windows 10 or later, run the Outlook startup troubleshooter.
   • Use the classic Outlook startup troubleshooter and follow the prompts in Get Help.

References:

• We're sorry, but Outlook has run into an error that is preventing it from working correctly. Outlook will need to be closed as a result. - Microsoft Q&A
• I can’t start Microsoft Outlook or receive the error “Cannot start Microsoft Outlook. Cannot open the Outlook Window”
• Something is wrong with one of your data files and Outlook needs to close