We were removing a broken flange after a friend advised us to try and separate it to weaken the seal. We used a flathead screwdriver and a hammer to wedge between the two. The outside pipe broke too. We tried to go to the next lip and planned to replace it. Now the elbow broke!! We are on a concrete slab. Yikes. Can we glue the pieces back or by one to work differently.

What type of pipe, cast iron, PVC?
If you are on a slab how could you be going to the next joint?

Your friend gave bad advice. Post pictures.

https://www.facebook.com/media/set/?set=a.423369411034161.84028.100000833165006&type=1

PVC

Go back and cut out ALL the broken fittings, You will need primer, PVC cement and the fittings you've broken. Now replace the broken parts. More questions? Just ask! Good luck, Tom