I have same problem. I tried the defrag of Live Mail database and now have the "Windows Live Mail could not be started....(0x800C0155,2) error.
I then tried Repairing Windows Live Essentials 2011 via Control panel.
Same issue.
I removed using CMD line method.
I reinstalled by downloading new installer.
I got the same error..... 0x800C0155,2.
I then ran uninstall using CMD line method.
Then deleted c:\program files x86\common files\windows live
I could not find program files\windows live
I also deleted C:\Users\Study\AppData\Local\Microsoft\Windows Live Mail
and C:\Users\Study\AppData\Local\Microsoft\Windows Live
Then I installed from the other online installer (older one... http://download.microsoft.com/download/F/1/F/F1FE75CE-C235-4250-9598-AEE5D854A7EA/wlsetup-web.exe
Now it starts but all my emails are gone.
Please help....