Can't extrude

[adanes]

I can't extrude this piece. I know i have loops but i don't know where and how to fix them! Can someone help me?

[JDMather]

First thing I noticed is that your sketch is not constrained.

Place (dimensioned) symmetrical sketch points and then create your spline.

The vertical line on the left side isn't, well, vertical.

There is a very very very very sharp point midway at top.  Nothing can be manufactured with a sharp point like that.

On the other side the point isn't evey symmetrical and loops over itself. 

I recommend you read this http://home.pct.edu/~jmather/skillsusa%20university.pdf ,

then perhaps do the Vacuum tutorial in my signature before you start your part over.