Installation of El Capitan on Intel Core Duo taking so far 2 days. What can I do? I am installing OS X El Capitan on a Mid 2009 MacBook Pro. Previously running an OS X 10.8.5. Incidentally my installation is taking now two days. I have tried holding down the power button but still no difference. It resumes where it stopped I feel frustrated and I want to return to my previous operation system. What can I do? Does it mean my machine has crashed? have I lost or can I recover my work? Making matters worse I can't tell what percentage of installation achieved? Apart from the bar that has moved from 0% up to around 75% and it's stagnant at that level. I am confused on what to do.

Any assistance?
Theres not much you can do if it still says installing after all that, i think the best and safest thing you can do now is book an appointment at the apple store. You could tamper with it and maybe fix it but at this point in my opinion just take in to the store.