If your website has been migrated to a different IP address (for example, if you have purchased an SSL certificate, or have migrated between servers), you may find that your local DNS cache is stale, and as a result you will be unable to view your website for a period of time (usually up to 4 hours). It may be possible to clear your DNS cache.
The first place to start is by clearing it on your local workstation:
Windows 8 and 10:
This will flush your DNS cache.
We would also recommend clearing your browser cache also. If that does not help, we would recommend restarting your internet router, as that may also cache the DNS result. If the above fail, your Internet Service Provider (ISP) may have cached the old IP address. If this is the case you'll have to wait for the cache to clear. To verify that it's definitely not an issue on the server, however, we would recommend that you ask a friend using a different ISP to check the site loads for them, and you may also ask that our team check it from a few locations for you, so we can verify that all is as it should be.