Computers can be difficult sometimes, and for as easy as they've become, they still sometimes do things you don't understand or didn't expect.
The best source for support with your Linux computer, aside from your nearest Unix guru, is the amazing Linux Questions.
On Linux Questions, you have an open forum where you can post questions, and usually receive a helpful reply within 15 minutes.
It's almost too obvious to mention, and yet it's the one place that many of us forget to look in a pinch: the internet.
Open your favourite search engine and type in your question. Chances are, with millions of people using computers and a growing portion of that using Linux, someone's been in the exact same position as you are. Quite probably, the answer will reveal itself with minimal research.