My minidisplayport suddenly seam to have been stop working

Hello!

I have been using a second monitor for musicproduction/schoolwork for a while now and one day when I came back from schol i pluged the adapter into my MacBook Pro and it would not feed any image to my second screen. I have been doing the same prodecur every time. I have also tried different screens, i have not been trying another adapter though, but really can these adapers really break?

I am mainly thinking that I, by misstake, have alterned somekind of setting declining my MacBook Pro from feeding video though my Minidisplayport.

The adapter is a Minidisplayport to HDMI (with sound)

I am running 10.7.4
On a Macbook Pro, Late 2011

8GB or ram, self extended(performed this procedur after i bought it)

Thanks!