Whenever I try to enter my phpMyAdmin, it gives me this error:
The mbstring extension is missing. Please check your PHP configuration.
I've looked all over the Internet for a fix, but all I've found is errors similar to mine, but not the same, or the exact same but there was no fix given.
I am also using Windows.

check your php.ini file in the root directory of your php installation. In the extensions part of the configuration you should find:
remove the leading ';' to uncomment and enable the extension so it looks like this:
restart your apache and it should work.
Edit: I just read that you are already using a webhost. Does your webhost have a interface where you can set php variables etc? Or a .ini file you can edit?
If not you may are forced to talk to the webhost and ask them to enable that particular extension.