1) If when logged into 000webhost.com your status is suspended
2) Or when visiting your website you are presented with similar page
Your account has probably been suspended/deleted so your best option is to
1) visit www.000webhost.com, create a new account using a new or different email address to previously used on 000webhost and then recreate/reupload your website/data using backups or local files you have.
2) You could upgrade to premium www.hostinger.com and you can then reupload your website and have no issues with limits.
Plus if you live chat the support team once you've purchased they can migrate the data from your suspended account.
Free accounts aren't eligible for backups therefore if your site was deleted/suspended you have no backups available sorry.
Reasons why this error occurs or suspension occurs is
You have too many visitors and over load free server resources.
This might be caused by crawlers crawling your site; use robots.txt to limit the crawlers.
If you are using WordPress with lot of plugins your site might be under attack, remove all plugins only keep the one that you are really need.
If you have many add-on installed, your site take too much resources to run.
Your script is taking to much server resources to run.