all my buying, watching a and selling history has gone
You are registered in the UK, but you are currently signed in to the US ebay.com site.
Try signing out here and signing in on the UK site:
https://www.ebay.co.uk/
However I do not see any currently listed or recent items for sale in this account. The last time you received feedback for selling was over a year ago.
Make sure you are signed in to the same account and the same site on both devices.
It is very easy to accidentally create a new eBay account by signing in using a social media account for the first time, or to be signed in to one account on one device and another account on another device.
If you are getting stuck in a sign-in or verification loop:
Try using another browser, or a private or incognito browser window. If that works, try manually erasing your eBay cookies in the original browser.
If your browser has Enhanced Tracking Protection, try disabling that. Or if you are blocking third party cookies, try disabling that blocking.
