Hi dalchina,
thank you for your response! I finally decided to save my data and make a complete reset - now running on Linux Mint. For now no more struggle with repair-and rescue partitions or...

Dear community,

please have a look on following record done by „Lubuntu Boot-Repair Disk“ after trying to repair the MBR.

Until yesterday my computer ran on Win 10 on sda3 installed as an...