Some developers put encrypted code in their themes.
The encrypted code is to prohibit users from downloading the free theme, modifying it, then removing credits of the original author of the theme so that the user can claim it as their own.
If you try to remove the encryption (Base64), your theme will break.
I don't agree with the practice of using encryption, but that's another discussion.
There are ways to remove it, but you'll have to search the internet for those methods.
Something else you may want to try, is go into Appearance > Themes > and make sure that your theme is the active one.
(i know that sounds too basic, but I've seen it happen)