If the battery is charged, your machine will run just fine off of the 65W power adapter. Problems come up when the battery get depleted. Of course this may not be your problem at all. Charge it up and see if it will boot from the optical drive, "C" key on start up with the disk inserted. Go to the second screen pull down menu to Utilities, Disk Utility and see if you can repair your hard drive. Let us know your results and we can proceed.