@osar said in lost speed dials:
I made a new user account in my windows 10 notebook, and deleted the old one
Your speed dials would be in the "Bookmarks" file in the "C:\Users\youroldusername\AppData\Roaming\Opera Software\Opera Stable\Default" folder. The custom thumbnails for those speed dials would be in the "BookmarksExtras" file there. So, if you have those files, you can use them to replace the existing ones for Opera on the new user account.
However, you said you deleted your old user account after you created a new one. If so and you chose to also delete the account's files, then everything is gone unless you enabled Opera Sync in that Opera and synced your bookmarks to the Opera Sync server where you can see that they're still stored at https://www.sync.opera.com/. If they are synced there, you can enable syncing of bookmarks in the new Opera, goto the URL opera://bookmarks find the "speed dial" folder for the other Opera, select those speed dials, copy and paste them into the "Speed Dial" folder for the new Opera.