mass effect 3 multy player

Have you downloaded all the DLC for the game? They're free, so just get them. Alternatively, it might be a problem with your router/ISP.

Hello,

I don't know what platform you're on, but I'm on the PS3 and I never could find a way to search games going on to begin with. (FYI it is common practice to put the platform in parenthesis beside your subject to aid the people helping you.) Other than that, I'd advise following HammerHead90's advise. It could be that, if you don't have all of the DLCs, you can't play with the people that do. Likewise, checking you connection would be another important step, although, if I recall correctly, you can't even access the Multiplayer portion without Internet access. Still, I'm on the PS3, if you are on a different platform it could function differently. Checking your connection can't hurt, though, and might turn something useful up.

If that doesn't work, know that sometimes it takes a very long time to get people to join. I often just start out alone and solo the first 2 or 3 waves before people join in mid-combat. If you can't join any game through quickmatch and no one joins you consistently after starting missions alone, it is beyond anything I can help with. You would need someone that works for Bioware or Electronic Arts...