I bought Mass Effect a while ago and I didn't play multiplayer. Shepard died, I was unhappy with the ending, so I reloaded and now I'm trying to play multiplayer. I played at first without any of the multiplayer dlc's and I could find matches at any time of the day. Then I found out about the other DLCs and I downloaded all of them using the DLC pack, and now I can't find any other players online. My internet connection is wrong, and I don't know why it isn't working.
For PC there is still a lot of players online all the time. For that make sure you go on Origin and install all the free DLC's - without those you won't find anyone.
If you can't find anyone, disable paid DLC's, as game only matches people with the same DLC settings.
What platform are you playing on? I play on Live and still get a decent amount of matches in short order. It's nothing like what it used to be a couple years ago, but there's still people playing.
If you install any multiplayer DLC, you need to install all the multiplayer DLC.
The multiplayer DLC is free and here are the names:
Resurgence Rebellion Earth Retaliation Reckoning
The matchmaking will only put you with players that have the exact same multiplayer DLC installed. When you are just starting out, having no DLC is fine - because other players who are starting out will also have no DLC and you will be matched with them.
After a few matches, you should install all the DLC to unlock the ability to get the extra characters and weapons in your packs.