I am personally not a big fan of bridges if they can be avoided or in your case, a double crown joined together. Did your dentist go over the option of a dental implant to replace the tooth? It would require extracting the front tooth and replacing it with a titanium implant and then a crown on top. That way, the other adjacent tooth is untouched. The tooth with the loose crown sounds like it is non-restorable (non-salvageable).
So how does a post become ruined in the first place? My dentist told me that the post is partially ruined underneath my crown. How does that happen? Reguarless if having insurance, I don't have the money to do an implant. My dentist did put my crown back in and believe it or not, it's the tightest and most stable it's EVER been. Should I just leave it alone for now and see what happens or will it eventually come loose again?
Its a chance you'll have to take if you want to leave it in. It may be fine or it may fracture or fall out again. If it falls out, its not a big issue as long as it doesn't continue to break underneath. I'm not sure where the break with the post is. You'll have to ask him what he means by partially ruined.