Hello,
You can add your new desired domain name through the hosting control panel (Account Manager > Domain Setup > Add New), move the files to the new one, if applicable, and then delete the old domain name.
The account panel informs you of the reason of your suspension https://x10hosting.com/panel
Please follow unsuspension request guidelines: https://community.x10hosting.com/threads/this-board-is-for-all-unsuspension-request.209292/
The full error for the "Could not execute your request" is highly important to determine what the issue is.
Alternatively, for mail settings, you could change the incoming and outgoing server address to the server address "x12.x10hosting.com"
It means your domain contains a phrase that is generally not allowed that could be used for malicious intent. Please follow unsuspension request guidelines.
https://community.x10hosting.com/threads/this-board-is-for-all-unsuspension-request.209292/
That is managed through the SitePad website builder or other installable software like Wordpress (using themes available) which is already available on free accounts
There is a starter plan, which is $11.95/yr USD. The Starter plan is similar to the free plan with some higher resource allotments. When logged into the account panel https://x10hosting.com/panel you can click on the upgrades button.