This wasn't a problem for most of them except one:
Aquiring the Blacksmith achievement. I lost this achievement and leveled him up before I noticed, which gave me a new achievement in the chain. Now no matter what character completes that quest I can't get the achievement. This isn't like a hard achievement that people work towards .. I mean, you can't NOT get this achievement. Its part of the story. EVERYONE gets this one.
Except me. I can't re-get it. Can someone help, please?