I am in way over my head.
I have used WordPress for other projects. I offered to finish my aunt's sites for her, because whoever had started working on them had failed to finish the project.
What I did not know:
She had a single ip address and all domains registered were aliased to the main domain.
The previous main domain had been canceled and one of the aliased domains reverted to the main.
When she re-instituted the domain and we made it the primary domain, it removed her other blog. I never backed it up properly because I did not know that was how it was going to happen. I have copies of the mysql, and most of the old files still seem to be there.
I have literally been doing this for weeks in my spare time. For the longest time I could not get the redirects to go where I wanted them to go. Then I learned about a mult-sites and realized that it looked like the previous person had probably been trying to set that up.
I enabled the multi-site. With some work I was able to get the aliased domain to redirect to a subdomain of the main domain that I wanted to use. However, despite going through everything I could find, I can't seem to get anything besides a 500 internal server error when I try to use the other domain. The main is fine.
I know all of this is vague and I'm sure that my answer is somewhere in this forum, but I've been searching and I've just realized that I'm still too much of a noob at this. If anyone can give me any advice it would be much appreciated. I apologize in advance for being totally ignorant.