Laptop Issues

When it comes to schoolwork, writing, or anything internet related, usually I do everything on my laptop (like most people).  Normally, that isn't an issue, but since my laptop is about 6 years old, it's starting to show its wear and tear.  Some of the buttons don't work, the volume isn't what it used to be, and the disk drive/memory is low.  At least that's what it said.  My laptop is supposed to have 60GB, but somehow, it says I've almost used all of that, which is impossible for even people who download a lot of stuff.  I only use my laptop for a few things, not enough things to take up that much space.  I even had a few people look at it and asked questions, but they're baffled.  It could be an error, but why is it like this?  Is it something that can be fixed?  What if the problem lingers?  I googled most of it and found out answer and that this was a common problem, but I still don't know what to do.  I wish technology didn't always have dumb issues like this.  We pay so much money for things, and yet, there's always something wrong.  It's just a pain, and another thing I have to deal with.