Your site can be suspended for various reasons, but most likely this will be because of an outstanding invoice on your account. If your site is suspended, please check the 'My Invoices' section in the 'Client Area'. Once you pay any outstanding invoices for the account that's suspended, it will automatically be unsuspended within 5 minutes.
For help on how to pay an invoice, please read the following help article - How do I pay an Invoice?
Information Sometimes your web browser can cache the suspended page for your site. If your site is still showing as suspended after 5 minutes of payment, please fully close and re-open your browser.
Information If your account is suspended but you don't have any unpaid invoices then please log into your 'Client Area' and contact us via the Support Ticket system for further help.