How do I adjust volume settings permanently?

Hi guys,

So my problem with iTunes is that everytime I start it, whether manually or automatically, my volume is on mute. By that I mean the knob is on the far left of the volume bar. This means that I have to manually increase the volume for the first song, every single time I open iTunes and it's starting to really frustrate me. My older sister gave me her old macbook pro but she doesn't know how it got to this kind of setting. I have a wake up alarm playlist that I want to use with Calendar Alarm in Automator and everything works perfectly except the volume is on mute. How do I fix this?!

Thanks in advance for any tips.