Hello,
First of all, to regain access to your site, you can simply delete the plugin’s directory. The directory to delete is wp-content/plugins/wallets-cp.
Since you did not mention the error, I can’t help you any further (see how to ask for support). Please answer both of the following questions:
1. Do you see an error message, either on the screen, or in your PHP log? If so, please copy the error here in full.
2. Does the error persist when you switch to a different theme, such as Twenty Twenty?
If the error goes away with Twenty Twenty, then this is a typical mistake that some theme developers do, and I’ll be able to help with that.
with regards