You can use the Sharkbite or Gatorbite connectors as a junction for copper and PVC. Sharkbite and Gatorbite connectors are "snap together" connectors available at Lowes or HomeDepot, you can put copper in one side and PVC in another.
You've already accepted, but to properly fix this:
I'll assume it's all polyethylene pipe (typically used for well piping). The fitting also looks like nylon, which in my experience is easy to damage and often leaks. I much prefer PVC (which is typically gray) or brass.
Take everything apart, remove the elbow, and throw it away. Heat the end of the poly pipe with a torch, both around the outside, and a tiny bit on the inside. You want it to be warm, but not melted/squishy/burning. Put on two clamps, then put the fitting in, and then tighten down the clamps (about 1/4" apart, give or take). Repeat with the other end.
If you've never done this, you may want to practice on some scrap pipe first, especially if you don't have a lot of extra to work with. If you do melt the pipe, you need to cut the end back and remove the melted piece.
Best Answer
You know what they say: nothing is forever -- except glued PVC parts. Well I don't know if they really say that but they should.
It's unclear exactly what situation you have, but if you have a glued part that is broken, the only option is to cut out the elbow and replace it with a new one. You might need to use a coupling to add on another 1" or so of pipe to get the elbow positioned correctly again.