Okay, all right. Everything works again. I can only say thank you. You have helped me a lot. Thanks alot...
One more thing, which probably brought me into this situation. Not all payouts from the pool Siamining.com had arrived in my wallet. But now everything is there. If that happens again. What can I do. Do I have to enter a command in the wallet?
It is my pleasure to help

Yes, sometimes the wallet might become "blind" for a transaction, it is a known bug. If that thing happens again, do exactly what you have done today: delete your wallet folder and use your recovery seed to force Sia to re-scan the blockchain
The journey can begin, now SIA Webwallet is Online as i say Weeks ago , also Pre Order for the Cards is open
Be aware that
most of the "web wallets" for Sia out there are just scams that will steal whichever funds you send there. We had in the past months dozens of cases of users scammed. Do not trust any web wallet, only the official Sia-UI that can be downloaded from the official Sia website:
https://sia.tech/get-started