Microsoft Outlook uses PST data files to store all your emails, contacts and calendar entries. However, sometimes these files become corrupt due to inadvertent changes in default Outlook settings, bringing your Outlook data on the brink of loss.
If you have an Exchange server, Gmail, Yahoo Mail or Hotmail which backs up all your emails, then you can easily reset Outlook to default factory settings. We are discussing here how you can repair Microsoft Outlook to reset to factory settings with few easy steps –
Step 1: Go to ‘Start -> Control Panel‘, and navigate here ‘Mail’. If you didn’t find ‘Mail‘ option, type ‘Mail‘ in search box and find ‘Mail‘.
Step 2: Now click ‘Mail‘, it will opened up ‘Mail Setup’ dialogue box.
Step 3: Click on ‘Show Profiles’ button under the ‘Profiles’ tab. Now Mail dialogue box will be opened. It contains list of profiles that set up on your computer.
Step 4: Select your profile from the list (In most cases it will just have one mail profile.) and click ‘Remove‘ and then press ‘OK‘. It will delete your profile and then all your Outlook settings will be reset to default.
Now restart your Microsoft Outlook to ensure that it is back to factory setting or not.
I hope it will work.
Also find here how to repair MS Outlook 2003.