Scouter and Mp3 menus don't show up in game

how do i fix this problem? instead of my scounter showing up, a HL mini desktop thing pops up.

Welcome to the forums.

If they don't pop up at all, by default:
Press F8 for mp3 menu and press F9 for scouter modes toggle.

If these don't work, you might need to re-bind the keys, or just use the MULTIPLAYER > CONTROLS to change these keys.