Others are having problems.   See if this is relevant to you:

https://community.ebay.co.uk/t5/Technical-Issues/Severe-failures-with-accessing-eBay/m-p/8039399#M37...

If not try clearing cookies or using a different browser.   If you want to contact ebay you can ring them or request they ring you on your phone only, not on a laptop or PC.   So view this link on your phone:
https://www.ebay.co.uk/help/eua?id=5190