oh so your machine name changed. you may have to reinstall over the exisiting install.
if that does not work, check that the sql service and sql agent service are using the domain account as the startup account under services. make sure that machine was logged in under that account. if that do not work try adding that domain account as a local admin. not the prettiest solution but it should get you running.
If one brings so much courage to this world the world has to kill them or break them, so of course it kills them. The world breaks every one and afterward many are strong at the broken places. But those that will not break it kills. It kills the very good and the very gentle and the very brave impartially. If you are none of these you can be sure it will kill you too but there will be no special hurry. Earnest Hemingway, A Farewell To Arms.