Yay! Glad it all worked out!
I think some themes from the Templates and Themes subforum have tutorials on how to add them, you can post here if some error appears during this xD

Well I added a spire and bookstore theme to the folder (in their own respective ones of course) and now the pages went blank again. I did look for a tutorial on how to add them but couldn't see anything.

After changing it to the default theme it goes blank? You could try following the "Admin side" and "default mysidia template" parts from Kyttias tutorial, she seems to explain it well and it might fit into what you are looking for http://mysidiaadoptables.com/forum/s...ead.php?t=4371

Well I changed my theme on the site to Spire but it still doesn't show anything. Blank. Can't even get in to reset the theme. ACP still works of course.

^ So in the template folder for Spire, are there any files at all? If not, you might want to try dropping them in again. Installing it incorrectly on the backend really can erase everything in the folder, so I'd double check.

Nope. Everything is in there. Checked through it all and everything seems ok. Its just everything seems blank. I can't even log out of the site to make a new user to test.

/changestyle/index/main or /changestyle/index/elements to revert it

Did you put the folder as 'bookstore' or 'spire' when in the admincp? (the folder might be named 'spire' instead of 'Spire') Did you extract the .zip (just checking in case, sometimes people forget)?

Sorted it. Apparently using a capital S or not on the theme or whatever the first letter of its name is make ALL the difference. Thanks everyone. :D

Yeah, you gotta write it exactly like the folder is named, including capitals xD
Glad it all worked out!