When ever I try to compile my map it saysMAP LEAKED .....
And there is a red string going around my map... I got no idea what is going on....

and now... it can't find my .prt file... what ever the hell that is...

it means some part of your map is open to the void. go to misc->next leak spot and it will show you where the leak is.

What that means is that you have light inside your map leaking out through some hole, into "outer space", as I call it. Your map has to be sealed shut, so to speak. The red line represents the light's path through your map. You can either try the suggestion mentioned above (which is probably easier), or you can follow the red line; the point where the line goes from outside to inside the map (or vice versa) is where the leak is.