There are two ways of doing this. firstly, if you have a second working computer you could plug this hardrive into the SATA or IDE cable (dependent on computer and hard drive), this will then give the other computer two harddrives and you can simply load that computers usual OS and copy the data from the newly installed harddrive. The second option is to buy or find someone with an external harddrive case, and put your harddrive into that case, and you can USB plug this into another computer to copy the files.
There is actually a third option as well, if your computers OS is still working you can plug an external harddrive into this (or a second harddrive but you will have to open up your computer), and then copy and paste your files on to the working harddrive.
If you are stuck and have no OS, go to the ubuntu website. This is a free Linux based OS, which is one of the best Linux operating systems around.