Hello,
Can you please email me a screenshot at info@dashed-slug.net?
Did the problem occur when you activated the main plugin or the CoinPayments extension?
To regain control of WordPress, simply go to your wp-content/plugins directory and delete either wallets or wallets-cp, whichever plugin caused the error.
To find out why this occurred, please send me all error messages you can find, if you see any on your screen. Additionally, you can enable debugging https://codex.wordpress.org/Debugging_in_WordPress and check the logs.
If there are no hints in the logs then I will need as much info about your setup as possible, PHP version, installed PHP extension, etc.
Contact me by email and we’ll figure this out.
Thank you