What page? Try going to the main eBay page rather than using a link. Or try starting from the site map page and navigating from there:
https://pages.ebay.com/sitemap.html
Try another browser to rule out browser issues.
Try another device to rule out device issues.
Try another network, such as by using a laptop or phone when not connected to your usual Wifi connection.
Try signing in to a different account, if possible, to see if the problem is actually related to one particular account.
For non-selling related tasks, you might try signing in to ebay.ca or ebay.co.uk -- from there you should still be able to read messages if you are having problems reaching ebay.com.
