Step 1: Use the Windows Live Writer Backup tool to backup your settings, drafts, plugins and save it to a safe location. It is very important you do this incase something goes wrong and you lose everything.
Step 2: Go to Add/Remove Programs or Programs & Features in Windows Vista and search for Windows Live Essentials and click on the Uninstall/Change button and uninstall Windows Live Writer.
Step 3: Go to your My Documents folder and rename the folder “My Weblog Posts” to something else, also go to the local settings folder and copy the Windows Live Writer folder and save it somewhere else, after you have created a backup, delete the folder from the Local folder.
In Windows Vista you will find this under C:\Users\username\AppData\Roaming in Windows XP you should find it under the Local settings folder for your user.
Please make sure you have backed up everything as suggested in step 1 before deleting anything.
Step 4: Once you have uninstalled WLW and followed step 3, directly download the Windows Live Writer application from here and install it.
Step 5: Once again use the Windows Live Writer Backup tool to restore the drafts, blog settings and plugins.
That’s it, hopefully this should fix a annoyance some of you have where Windows Live Writer does not start at all.