Now that you've provided a teensy bit more of what the posting tips suggest....
we can at least look at the site.
You have problems all over the site. Not just the admin. Currency won't change, can't add to cart, etc.
You might want to give us all the answers to the posting tips. It could help us narrow down the suspects. It could be a mod or that you have the define(STORE_SESSIONS', '') set to db in the configure.php files. It could also be a mod or that your host has installed encryption.
We need more info.
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