How to repair database/index?

Hi all,

It seems that the machine crashed, and since then I can’t find any results anymore (very slow response as well). How can I run a repair on the index/database?

Also, I cant login anymore as administrator and changing the password also didn’t work with both proposed solutions described at https://yacy.net/faq/.

Thanks for any pointer!

Update: after a new setup, the attached NAS was disconnected and it happend again.
The OS booted fine, but YaCy could not be used anymore, probably due to index inconsistencies.
OS: Debian 9 (installed latest Debian package), ext4, RAM: 8G, YaCy heap: 3G