I've had my my Logitech speakers for a few months now and they've worked fine up until a few weeks ago. Now if I turn the volume up more than a quarter of the way the sound goes scratchy and worsens if I turn it up even more.. Any ideas on how to fix this or do I need to get new speakers?

The speakers plug/outlet is usually at the back of the computer you will have to open up the computer to check the lead attached to the rear of the input plug make sure the connection is good
or you might have to clean the dust from your computer dust causes static which causes your computer to overheat and all sorts of problems
be sure to wear an anti static earth strap before touching anything inside your computer try cleaning your computer of dust using a fine air blower from a compressor making VERY sure that there is no MOISTURE in the air line specifically around the CPU central processing unit and your SOUND CARD dust causes static to build up in a computer causing it to overheat any many other problems
hope this helps