If your VPS down, try to access from another PC or using proxy like rxproxy.com to ensure that your Ip is not blocked.
If still you are not able to access, it's possible that your VPS is out of memory. What you need to do are:
1. go to master.sosys.net:5353
2. go to your VPS details (Manage)
3. Look for "Reboot" button and click on it.
4. Wait for about 10 minutes.
Otherwise, you can go to the console by clicking on "Serial Console" and key in the console password and your root password to see the progress.
If still it does not go up, it's possible that you are required to upgrade your memory. Contact us via firstname.lastname@example.org for more info.