That model is over 5 years old and out of AppleCare and likely is dead.
Call or take it to a local professioanl that fixes Mac's and see what they say, it might be time for a new machine.
The internal hard drive can be removed and a SATA to USB adapter combined with Apple's Migration Assistant can move your files and apps to a new Mac.
If your not going to get a new Mac, but a Windows machine, then there is MacDrive, install that on the Windows machine and use the SATA to USB adpater to transfer what files you can and will work with Windows versions of software. Text, jpgs, standard (non-propretary formats) pictures, movies and music files etc all pretty much work there too. Just different programs, some Apple ones like iTunes are available for Windows.